Since the end of the Great Recession more than 12 years ago, growth stocks have been dominant. Historically low lending rates and a persistently dovish U.S. central bank have given fast-paced companies access to cheap capital that they've used to hire, acquire, and innovate.

The thing is, even with growth stocks responsible for pushing the stock market to new heights, great deals can still be found. For long-term investors, the following three surefire growth stocks are all bargains that can be confidently bought in December.

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Square

The first surefire growth stock patient investors can load up on in December following a 25% pullback since August is fintech-giant Square (NYSE:SQ).

For the past couple of months, Square has come under pressure for a variety of reasons. There's worry about the role cryptocurrencies might play in the payments space, and more recently, there's concern about higher-inflation rates adversely impacting consumer spending. Growth stocks with hefty premiums tend to get hit hardest when inflation picks up.

While these might be tangible concerns for some fintech stocks, Square has demonstrated it's in a class of its own -- which is why it carries such a lofty valuation premium.

For more than a decade, the company has relied on its seller ecosystem as its bread-and-butter growth source. This segment is what provides point-of-sale solutions, loans, and analytics to help businesses succeed. In the seven years leading up to the pandemic, the gross payment volume (GPV) transacted on Square's network grew by an annualized average of 49% from $6.5 billion to $106.2 billion. Based on Square's third-quarter GPV of $41.7 billion, the company has an annual run-rate of almost $167 billion. 

What's remarkable about the seller ecosystem is its incorporation of bigger businesses. Once a tool used almost exclusively by small/independent merchants, two-thirds of Square's Q3 GPV originated from sellers with at least $125,000 in annualized GPV. Since the seller ecosystem is predominantly a fee-driven segment, this steady shift will gradually increase gross profits over time.

But the long-term growth opportunity that should make Square a surefire investment is its digital peer-to-peer payment platform, Cash App. In just a three-year stretch ending Dec. 31, 2020, Cash App's monthly active user (MAU) count more than quintupled from 7 million to 36 million.

What makes Cash App so intriguing is its margins. In the June-ended quarter, Square noted in its shareholder letter that it was generating $55 in gross profit per monthly transacting active customer, yet was spending around $5 to acquire each Cash App MAU. There's little question that Cash App will blow past the seller ecosystem in terms of profit potential over the long run.

The icing on the cake for Square is its pending $29 billion acquisition of "buy now, pay later" company Afterpay. Purchasing Afterpay will create a closed-loop payment system that connects the seller ecosystem with Cash App. This pricey deal is ultimately geared at growing its ecosystem and bolstering long-term margins.

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Novavax

Another surefire growth stock investors can confidently pile into in December is drug-developer Novavax (NASDAQ:NVAX).

Novavax is one of what's seemingly become an army of drugmakers angling to produce a coronavirus disease 2019 (COVID-19) vaccine or treatment. But unlike most of the crowd, the company's lead vaccine (NVX-CoV2373) appears to be in the upper echelon of effectiveness.

In March and June, Novavax released the results of two large-scale studies involving its COVID-19 vaccine. In the U.K. trial, NVX-CoV2373 produced an 89.7% vaccine efficacy (VE), which included the original strain of the SARS-CoV-2 virus that causes COVID-19, as well as the U.K. variant. There was also the U.S./Mexico phase 3 trial, which produced a 90.4% VE. With the exception of Moderna and Pfizer/BioNTech, whose initial large-scale U.S. trials yielded respective VEs of 94.1% and 95%, Novavax looks as if it'll slide in as the clear No. 3 option in the COVID-19 vaccine space.

Despite these positive clinical results, Novavax's share price has more or less gone nowhere since late January. This has to do with emergency-use authorization (EUA) filing delays in key markets, as well as production setbacks. Wall Street and investors have been quick to pounce on any delays in bringing NVX-CoV2373 to market.

However, Novavax looks like it's working through many of its delays. It was recently granted its first EUAs in Indonesia and the Philippines and has filed for the equivalent of EUA approval with the World Health Organization, Canada, Australia, and the U.K., to name a few key markets.

It's important for investors to understand that COVID-19 has the look of an endemic illness. The mutability of the virus, coupled with the need to vaccinate billions of additional people worldwide, makes it highly likely that Novavax will generate recurring revenue from this indication, rather than a one-time pop from initial inoculations.

The Novavax growth story should also blossom, thanks to innovation. It's one of the leading candidates to develop a combination COVID-19/influenza vaccine and bring it to market faster than its peers.

All of these factors make Novavax a screaming bargain in the biotech space.

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Pinterest

A third surefire growth stock to buy in December is social-media platform Pinterest (NYSE:PINS).

There's no sugarcoating that Pinterest has been a dud in 2021. Its shares are down almost 40% year to date, with the stock teetering on a 14-month low. This weakness is the result of Pinterest's MAU declining on a sequential basis for each of the past two quarters (from 478 million in Q1 2021 to 444 million in Q3 2021).

To state the obvious, Pinterest was never going to maintain its rate of MAU growth achieved during the pandemic. With COVID-19 vaccination rates picking up in developed markets, it's not a surprise to see people getting out of the house more often. But it's worthwhile noting that, when examined over a three-or-five-year period, Pinterest's MAU growth remains within historic norms.

What's far more important for investors to recognize is that, even with more modest near-term MAU growth, we're seeing almost no slowdown in the monetization of Pinterest's user base. In the September-ended quarter, global average revenue per user (ARPU) jumped 37%, while international ARPU skyrocketed 81%. International ARPU remains low enough ($0.38 in Q3) that it can double many times over this decade and fuel sustainable double-digit growth.

What's made Pinterest a desirable place for advertisers is its transparent operating model. Whereas other social media platforms gather information with likes and users' search histories, the entire premise of Pinterest is for users to post about the things, places, and services that interest them. With this important data in hand, Pinterest merely needs to connect users with the merchants who can meet their needs. It's a no-brainer that merchants are going to be willing to spend big to reach motivated shoppers.

Following its retracement, Pinterest is downright inexpensive. It can be scooped up for 30 times Wall Street's forecast earnings per share for 2022, yet is still growing sales by 25% or more annually. It's the perfect growth stock to add in December and hang onto over the next five to 10 years.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.