• Line two large baking pans with parchment paper. We will put 6 doughs on each pan later

Prepare the dough:

• Put all ingredients for the dough in a bowl of a stand mixer and use the dough hook to stir everything first so the dry ingredients won't fly all over when you start the machine.
• Start mixing on the lowest speed for about 2-3 minutes and then turn the speed up a notch and knead for another 3-4 minutes. Stop the machine and scrape the sides of the bowl and start the machine again, one speed higher than before and mix for another 5-8 minutes until the dough is smooth and elastic. It will clear the sides of the bowl but still stick to the bottom of the bowl. This dough is meant to be sticky and soft. Please don't be tempted to add more flour. You may need to scrape the sides of the bowl several times throughout the kneading process
  
• Lightly oil the bowl and your hands and form the dough into a ball and place it back into the mixing bowl or move to a different container (oil them to prevent sticking)
  

First proofing:

• Cover the dough and let it rise at a warm place until the dough is doubled in volume. It may take 1 1/2 - 2 hours depending on temperature. When you press with your finger, the indentation stays and the dough does not deflate
  

Prepare the filling, topping, and crumbles: (can be prepared few days before and kept in the fridge)

• Place the diced peaches, sugar, cornstarch in a saucepan and let them sit for 5 minutes. The sugar will draw out some liquid from the peaches. Turn on the heat on medium and let them cook until bubbly and thickens, about 10 minutes. Stir the mixture every now and then to prevent burning at the bottom of the pot. Let it cool down completely
  
• Combine softened cream cheese, powdered sugar, egg yolk, and lemon zest in a small bowl. Mix to combine. Cover and set aside
• Melt some butter and let it cool down. Combine flour, ground cinnamon, brown sugar, granulated sugar and pinch of salt in a small bowl. Add the melted butter and use a fork to stir them. The reason we use fork is to prevent overmixing the crumbles. If you overmix too much, the mixture turn into a paste. There will be small and big clumps. Cover and keep them chilled in the fridge while you work on other things
  

Back to the dough:

• Once the dough has doubled in volume, deflate the dough by folding the edge towards the center several times. Divide into 12 equal pieces. Roll each one into a round dough ball
  

Final proofing:

• Place 6 dough on each pan, about 2-3 inches apart. Cover with a lightly oiled cling wrap and let the dough rise again at a warm place, this can take about 45 minutes to 1 hour. The dough should feel light and puffy
• 10 minutes before the end of proofing, preheat the oven to 375 F (190 C) for conventional oven, 350 F (180 C) for convection oven
• Position the oven racks, 3rd from the top and 3rd from the bottom

Assembling:

• Use the flat bottom of a 1/4-cup measuring cup to create a deep indentation on the dough. Flour the bottom of the cup and then press it on top of the dough, all the way down to the bottom. The cup should touch the bottom of the baking pan. Repeat with each dough
  
• Brush the sides of the dough with egg wash.
  
• Divide the cream cheese filling into each cavity.
  
• Put the peach topping on top of the cream cheese.
  
• Sprinkle the crumbles on the side of the dough, and some on the peaches
  

Baking:

• Place the baking pan in the positioned racks. Bake for 10 minutes and then rotate the pan top to bottom, front to back so they bake evenly. Continue baking for another 10 minutes until the kolaches are just lightly golden brown. Do not overbake them
  

Cooling:

• Remove from the oven and let them cool on the pan for about 5 minutes and then move to a cooling rack to let them cool down to warm
  

Serving:

• Kolaches are best served warm on the same day they are made

Storage:

• You can store leftovers in an air-tight container for 2-3 days. Just make sure they have cooled down completely before you do that. When ready to serve, you can heat it up slightly in microwave. Cover with a damp paper towel and heat on high for 10 seconds or until heated through to your preference