1.In a 2-cup liquid measuring cup add 1 cup milk, 10 tablespoons melted butter, 1 egg, and egg yolks together. Whisk 3 1/2 cups flour, 1/3 cup sugar, yeast, and salt together in a bowl of a stand mixer. Fit stand mixer with dough hook.
2.Add milk mixture to flour mixture, and knead on low speed until no dry flour remains, about 2 minutes. Increase speed to medium and knead until dough clears sides of bowl but still sticks to bottom, 8 to 12 minutes. Take dough out of the bowl and spray with cooking spray. Add dough back in and cover with plastic wrap. Set aside to proof for 2 hours until doubled.
3.Meanwhile, using stand mixer fitted with paddle, beat cream cheese, 3 tablespoons sugar, 1 tablespoon flour, and lemon zest on low speed until smooth, about 1 minute.
4.Add ricotta and beat until just combined, about 30 seconds. Transfer to bowl, cover with plastic, and refrigerate until ready to use. In a small bowl crack 1 egg and add 1 tablespoon of milk. Whisk well and place in the fridge.
5.Combine 2 tablespoons and 2 teaspoons flour, 2 tablespoons and 2 teaspoons sugar, and 1 tablespoon frozen butter cut into cubes in a bowl. Rub the mixture between fingers until mixture resembles wet sand. Cover with plastic and refrigerate until ready to use.
6.Line 2 rimmed baking sheets with parchment paper. Punch down dough and place on lightly floured counter. Divide dough into quarters and cut each quarter into 4 equal pieces. Form each piece into rough balls by pulling dough edges underneath so top is smooth.
7.Arrange 8 balls on each prepared sheet pan and cover loosely with plastic wrap. Let dough rise until doubled, about 2 hours.
8.Heat oven to 350 degrees. Grease and flour bottom of 1/3-cup measuring cup. Make deep indentation in center of each dough ball by slowly pressing until the cup touches the sheet pan.
9.Gently brush kolaches all over with egg-milk mixture. Divide filling evenly among kolaches (about 1½ tablespoons per kolache) and smooth with back of spoon.
10.Sprinkle streusel over kolaches, avoiding filling. Bake until golden brown, about 25 minutes, switching and rotating sheets halfway through baking. Let kolaches cool on pans for 20 minutes then transfer to a cooling rack. Serve warm.