In bowl mix your water, sugar and yeast and set aside to proof for about 5-10 minutes.
Once foamy, add in your salt and butter and stir to combine.
1 cup at a time add in your flour and mix well, pour out onto a flour lined countertop and knead, adding more flour as your go to reduce stickiness.
Once all lumps are out and dough is smooth and slightly sticky place in a large bowl sprayed with cooking spray and flip to coat all sides.
Cover and place in warm draft free place to rise for about an hour or until double in size.
Once risen remove from oven and spray countertop with non-stick cooking spray and turn your dough out.
Cut into 6-8 equal sized pieces, pull each of your pieces to about 18-24" length and flatten with palm of hand.
Spread some of your mozzarella cheese down the center or each piece of dough and then pinch edges to close, grab each end and twist into a pretzel shape and slightly flatten, repeat with remaining dough.
Preheat oven to 450.
Meanwhile bring your water and baking powder to a boil, add one pretzel at a time into the water and boil for about 30-60 seconds, remove with slotted spoon and place on baking sheet.
Repeat with all remaining pretzels.
Mix together your egg and 2 Tbs water and brush over the tops of each pretzel, top with pepperoni slices and sprinkle with mozzarella cheese.
Bake in oven in batches for about 10 minutes or until cheese is melted.
Serve with marinara sauce and enjoy!