Preheat the oven to 350°F.
In a large saucepan over medium heat, warm the cream until just below scalding.
In a large bowl, whisk the egg yolks and sugar until blended. Slowly add the warm cream to the egg yolks, whisking constantly. Whisk in the vanilla.
Butter a 9-by-13-inch baking dish. Place the torn croissants inside, drizzle with the melted butter, and toss to coat and combine. Pour the base over the croissants, toss to coat, and let stand for 15 minutes.
Bake 50-55 minutes until golden and a knife inserted into the center comes out clean.