Blintz soufflé is a Jewish casserole that’s prepared from frozen cheese blintzes that are topped with an egg-based custard that also includes sour cream, orange juice, and just the right amount of sugar.
Place an oven rack on the center shelf and preheat the oven to 350 degrees F.
Melt the butter in a small saucepan, then pour half of the butter evenly into a deep 9x13-inch casserole dish.
Place the frozen blintzes on top of the butter, lining them tightly against each other in a single layer along the bottom of the pan (I was able to fit 2 rows of 7 blintzes). Drizzle the remaining butter evenly on top (it will solidify as it touches the blintzes, so don’t worry about getting a perfectly even coating).
In a large bowl, use a whisk or spatula to combine the sour cream, sugar, salt, vanilla, and orange juice until thoroughly combined.
Separate the egg whites and yolks between two separate medium-sized bowls. Using a whisk, beat the egg yolks until pale and fluffy. Using an electric hand mixer (or stand mixer), beat the egg whites to a soft peak.
Using a spatula, stir the yolks into sour cream mixture until evenly combined. Next, stir in about 1/3 to 1/2 the egg whites until smooth. Gently fold in the remaining egg whites. Pour the entire mixture over the blintzes, smoothing out the top with a spatula.
Bake until the top is a deep golden brown, 50-60 minutes. The soufflé will puff up while baking. If it looks like your oven is browning the top unevenly, gently turn the casserole dish in the oven midway through.
Allow to cool slightly before cutting into the blintz souffle. It often deflates a bit while cooling, which won’t impact the overall souffle texture. Optionally serve with sour cream and a sprinkle of sugar.
Store leftovers in the refrigerator in the covered casserole dish, and enjoy within 3-4 days.