Warm Lemon Pudding

Name: Warm Lemon Pudding
Cuisine: American
Ingredients: Four servings; 3/4 cup (150g), plus 2 tablespoons (30g) of sugar; 1 tablespoon (15g) salted butter, at room temperature; 2 lemons, for the zest and to get 1/2 cup (125ml) freshly squeezed lemon juice (depending on the size of your lemons, you may need an extra lemon to get enough juice); 3 large or extra-large eggs, separated (put the egg whites in a medium-size metal or glass mixing bowl); 1 cup (250ml) whole milk; 3 tablespoons (30g) all-purpose flour; Powdered sugar, for finishing