Step 1

Preheat the oven to 400 degrees F (200 degrees C).

Step 2

Brush butter on the bottom and up the sides of two 5 1/2-ounce ramekins. Scoop in some sugar; rotate ramekins to coat while pouring most of the sugar back into its container. Place ramekins on a shallow baking pan.

Step 3

Separate eggs between 2 bowls. Add sugar, flour, 1/4 teaspoon salt, vanilla extract, lemon zest, cream cheese, and Cheddar cheese to the yolks. Mix the souffle base with a spatula until sugar and flour disappear.

Step 4

Sprinkle a pinch of salt over the room-temperature egg whites. Beat with a whisk until soft peaks form; peaks should hold their shape but not be stiff or dry. Stir and fold 1/2 of the egg whites into the souffle base until combined. Gently fold the rest of the egg whites into the batter.

Step 5

Fill ramekins up to the lip with the batter.

Step 6

Bake in the preheated oven until puffed and browned, about 12 minutes. Serve immediately.