In a medium bowl, combine flour and boiling water. Stir until the mixture gathers into a shaggy mass. Shape into a ball, wrap in plastic, and refrigerate overnight.
For the Dough
In a mixing bowl, sprinkle yeast over warm water. Let sit for 5 minutes. Add sugar, egg, salt, and melted butter. Stir with a wooden spoon.
Add the overnight dough, gradually adding flour until it forms a soft, shaggy dough. Knead on a floured surface until smooth and elastic.
Shape into a ball, place in a bowl, cover, and let rise for 1.5 hours until doubled in size.
Deflate dough, divide into 14 portions. Flatten, fill with cheddar, and shape into balls. Place in greased muffin pans.
Cover and let rise for another hour. Preheat oven to 350°F.
Brush with egg wash, sprinkle with garlic powder, cheddar, parmesan, and sesame seeds. Bake for 18-22 minutes until golden.
Notes
Store leftovers in an airtight container to maintain freshness.