Combine the yeast with lukewarm water and let it sit for 3-5 minutes until foamy—this confirms the yeast is active and ready to leaven your kolaches. Once foamy, add the milk, sugar, and room temperature egg, stirring until combined. This mixture creates the base for a soft, enriched dough. Stir in 1 1/2 cups of flour until you have a shaggy mixture.
Add the salt and butter to the mixture from Step 1 and stir until the butter is mostly incorporated into the dough. The salt enhances flavor while the butter will add richness and tenderness to the final kolaches. Gradually add the remaining 1 1/2 cups flour, stirring until the dough comes together and is slightly sticky but holds its shape. I find that the dough texture should feel like it could stick to your hands if you pressed it, but it shouldn't be wet or overly loose.
Cover the dough from Step 2 and let it rise in a warm place for about 1 hour, or until it has doubled in size. On a lightly floured surface, roll the dough to 1/2 inch thickness and cut it into 2 1/2 inch circles using a cookie cutter or glass. Place the rounds on parchment-lined baking sheets, cover them loosely, and let them rise for 45 minutes. The dough should become puffy and light—this second rise creates the tender, pillowy texture that makes kolaches special.
While the dough is rising in Step 3, blend together the cream cheese, egg, sifted icing sugar, vanilla, and lemon zest in a bowl until smooth and creamy. The lemon zest adds a bright note that complements the raspberry beautifully, and sifting the icing sugar prevents lumps that would make the filling grainy. Set the filling aside until you're ready to fill the kolaches.
Preheat your oven to 375°F while your dough is finishing its second rise. Once the dough rounds are puffy, gently press a deep well into the center of each one using your thumb or the back of a spoon—be careful not to press through to the bottom. Spoon about 2 tablespoons of the cheese filling from Step 4 into each well, then add 1-2 teaspoons of raspberry jam on top. The jam sits on the cheese filling so it stays in place during baking and creates a beautiful jewel-like appearance.
Brush the edges of each kolache with a beaten egg wash to give them a golden appearance, then bake at 375°F for 11-14 minutes until the edges are lightly golden and the cheese filling is set. The kolaches are done when the edges are set but still tender—they shouldn't be dark brown. Remove from the oven and let them cool on the baking sheet for a few minutes, then transfer to a wire rack. Once completely cooled, dust lightly with sifted icing sugar for a delicate, finished look. I like to serve these slightly warm with a cup of coffee for the best texture and flavor.