Yeast Activation: In a mixing bowl, dissolve the sugar in warm water, then sprinkle the yeast over the top. Let it sit for about 10 minutes, or until frothy.
Mixing the Dough: Add flour, salt, and olive oil to the yeast mixture. Using a dough hook attachment, mix at medium speed until a soft dough forms. For less stickiness, add a little more flour.
Cheese Incorporation: Gently fold in the shredded cheddar and mozzarella cheeses until evenly distributed throughout the dough.
First Rise: Cover the bowl with a damp cloth and let the dough rise in a warm place for about 1 hour, or until it has doubled in size.
Shaping the Loaves: Punch down the dough and turn it out onto a lightly floured surface. Form each into a loaf after dividing it in half.
Second Rise: Place the shaped loaves onto a baking sheet lined with parchment paper. Place a clean kitchen towel over them and wait 30 minutes.
Preheating the Oven: Preheat your oven to 375°F (190°C).
Egg Wash and Topping: Beat the egg with a tablespoon of water and brush it over the top of the loaves. For extra flavor, you can sprinkle sesame seeds on top.
Baking: Bake in the preheated oven for 35 minutes, or until the bread is golden brown and sounds hollow when tapped.
Let the bread cool on a wire rack for a few minutes before cutting it.