The Italian, appointed in July, cracked open some champagne in honour of the occasion.
"Champagne and pizza is good," Ranieri told reporters. "I'm very happy. I'm pleased with our attention and also in the last 10 minutes we showed our character, our fitness, everything.
"I (will) ask them when they want to eat pizza," he added of the promise he made last month. "It's carbohydrate, good for the muscles."
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Despite Leicester's lofty position, Ranieri said his team would not get carried away and that avoiding relegation was still the goal.
"We must achieve 40 points to be safe," he added. "Now 21 (more) because that is my philosophy."
Vardy drew special praise. The England striker has 10 league goals this season, four more than his closest rivals, and turned in another hard-working performance against Palace.
"I tell him every time you play for the team, continue to fight, continue to press, continue to run, continue to attack the line, the defensive line, that's as important," said Ranieri.
"You can score or you can't score. The performance must be good."
Vardy will be among the players rested for Tuesday's Capital One Cup tie away to Hull City, however, the manager told a news conference on Monday.
"I change a lot because I have a very good group and they deserve to play, so I change everybody more or less," he said.
"But we want to win of course against a very good team."
(Reporting by Simon Jennings in Bengaluru; Editing by Tony Jimenez)
