Warm the milk: In a microwave-safe bowl, warm the milk in the microwave for about 1 minute, until it’s between 98°F to 105°F.
Mix the Wet Ingredients: In a large mixing bowl, whisk the warm milk with the sugar, instant yeast, eggs, and softened butter.
Add the Dry Ingredients: Add the flour, nutritional yeast, Italian seasoning, and salt. Mix with a large wooden spoon until it forms a soft dough.
Knead the Dough: On a clean work surface, knead the dough by hand for about 5 minutes, until the dough is smooth and elastic. (Or knead the dough in a stand mixer with a hook attachment for about 3 minutes.)
Let the Dough Rise: Place the dough ball back in the mixing bowl and cover it with a clean kitchen towel. Let the dough rise in a warm spot until it has doubled in size, after about 1 hour.
Make the Filling: In a small bowl, mix the softened butter, garlic powder, and salt until it forms a thick paste. Set aside.
Fill and Cut the Dough: Grease a 9-inch by 5-inch loaf pan and set aside. On a clean work surface, roll out the dough until it’s about 12 inches by 16 inches. Spread the garlic butter over the dough in an even layer, all the way to the edges. Cut the dough into 12 even squares (4 inches by 4 inches) (3 squares by 4 squares). Sprinkle the shredded Parmesan and cheddar evenly on top of each square.
Shape the Dough: Fold each square of dough in half and place it in the prepared loaf pan so the folded side is facing down in the pan, and the open side showing the filling is facing up. To get all the dough pieces to fit, gently press the ones in the loaf pan towards the edge to make room for the rest.
Proof the Dough: Cover the loaf pan with a kitchen towel. Set aside to proof for 1 hour, until the loaf has puffed up. The dough is done proofing when an indent made by your finger springs back to its original shape after 2-3 seconds.
Bake the Bread: Preheat the oven to 350°F. Bake for 40 to 50 minutes, until the loaf is golden brown and reaches an internal temperature of 190°F–200°F. I usually add a large piece of aluminum foil folded in half over my bread after 20 minutes, to prevent the top from getting too dark. Allow the loaf to cool for 10 minutes, then remove it from the loaf pan to tear & share!Optional: Brush the top with a little melted butter and sprinkled with fresh chopped herbs or extra shredded cheese.