It's no secret that Apple has lofty ambitions in the health-care space. Now, it's time for the company to make "a big, splashy acquisition" to prove it's serious, says CNBC's Jim Cramer.

"Apple has a problem here," he said Tuesday. "As much as we might love the service revenue stream created by all these apps, including the health-care ones, most investors treat Apple like it's some kind of hardware company ... on the verge of becoming obsolete."

The problem stems from the iPhone, Cramer, host of "Mad Money," explained. In 2018, iPhone sales accounted for 63 percent of Apple's revenue, so the moment they started to decline, investors wrote the company off.

But with an installed base of 1.4 billion users, a growing ecosystem of apps and services and goals of becoming a leading force in digital health care, Apple has a lot more going for it — it just needs to show Wall Street, Cramer argued.

"It's time for them to make a big, splashy acquisition ... in the software space," he said. "The idea here is that this would make the service revenue stream a larger piece of the pie. [...] Perhaps more important, it would force investors and analysts to reevaluate Apple as more than just a hardware company."

And, to the "Mad Money" host, the answer seemed obvious.

"Apple should acquire Epic Systems. That's a privately held provider of electronic health records," Cramer said. "Not only would this deal be good for the company, I think it's exactly what Apple's stock needs to get its mojo back."

Epic Systems specializes in making health records digital. Unlike Cerner, one of its few large-scale competitors that caters to broader health-care networks, Epic focuses on hospital systems and independent practices.

But the electronic health record-keeping business isn't as seamless as it appears. Because it's still a competitive space, companies often engage in "information blocking," or refusing to share data between their networks. In other words, if your doctor uses Epic, but you go to a hospital that uses Cerner, they might not be able to pull your records.

That's where Apple comes in, Cramer said. A year ago, the company rolled out a service that allowed iPhone users to access their own medical records by linking up to participating hospitals.

"If electronic health records are ever going to achieve their full potential, you need something to act as a universal repository for all this data, and the iPhone and Apple could easily do it," he argued.

"If Apple wants to become the universal electronic health records provider, to be the handshake between, say, the Watch's data and the system, they're going to need to break into this market big, and the best way to do that is by acquiring the best: Epic," he continued.

While Epic's market capitalization isn't public, the publicly traded Cerner has a market value of nearly $18 billion. Though, with $123 billion in cash, Apple can afford most anything, Cramer argued.

Cramer preferred Epic over Cerner for its top-tier status — it's been named the No. 1 software suite by Klas Research for eight years running — and its no-frills structure. The private company has never made an acquisition, meaning it would be easier for Apple to integrate than a giant like Cerner, he explained.

Another interesting point: Epic Systems founder and CEO Judy Faulkner, who owns 43 percent of the company, is now 75 years old and has said on the record that she does not plan to bring Epic Systems to the public market. She has also reportedly created a charitable foundation to take over nearly all of her shares in Epic when her time as CEO is finished.

"If she wants to retire with a bang, selling her company to Apple would be a good way to do it, especially because a deal like this one could potentially be revolutionary for the health-care sector," Cramer said.

He added that, sooner or later, the business will inevitably scale, and he'd rather have the privacy-conscious Apple control millions of health records than other tech giants.

"Bottom line? With iPhone sales slowing, Apple needs to do something to jump-start its stock price and the service revenue stream," Cramer said. "I think a big acquisition that bolsters its service business would do the job, and buying Epic Systems to double down on health care and give the handshake between [the Watch] and all of the health-care system ... could do it. So, come on, [Apple CEO] Tim Cook and Judy Faulkner. Make this one happen."