Preheat oven to 180°C (approximately 350°F). Grease wells of a mini muffin tin and place in the freezer.
Pour flour into a large bowl and create a well in the center.
Mix crumbled yeast with 1 teaspoon of sugar and 5 tablespoons of lukewarm milk. Pour into well and cover bowl. Let rest for 15 minutes in a warm place.
Add remaining milk, butter and egg to the dough and knead well. Let rest for another 30 minutes.
Add bacon and cheese and knead well.
Divide dough into 24 portions and place in the mini muffin wells. Cover and let rest for 15 minutes.
Brush mini muffins with egg yolk. Bake for 20-25 minutes. Let rest in tin for 5 minutes before removing. Serve warm.