Britney Spears -- Big Stiffer, Big Tipper!

Britney Spears just brought a piece of Vegas to the Cheesecake factory she stiffed ... because her waitress just hit the jackpot.

TMZ broke the story, Britney chewed and screwed Sunday when she walked out of the Thousand Oaks, CA restaurant without paying her $30 bill for an appetizer and salad. Britney says she thought her security guy paid the tab and he thought she did.

Now she's bringing in the ultimate peacemaker to make things right -- Benjamin Franklin. Our Britney sources tell us the waitress is getting a $100 tip -- more than 300%. That's on top of the $30 tab.

We're told Britney -- who left with hard evidence of her heist (a doggie bag) -- felt terrible about the mistake.

Britney -- she stiffs good.