Preheat oven to 400°F.

Sift together the flour, sugar, baking powder, and salt in another large mixing bowl. Cut unsalted butter into small chunks and add to bowl or use a cheese grater to grate butter into smaller pieces.

Use a fork to incorporate the butter into the flour mixture until it forms a crumbly texture. Add milk and stir the dough until it is thick and pulls away from the sides of the bowl.

Transfer dough to a lightly floured, flat surface. Pat the dough down to about 1-inch in thickness, fold in half, and pat down once more to 1-inch in thickness. Cover with a towel and let rest for 30 minutes.

While dough rests, combine chicken, cream cheese, spinach, mozzarella cheese, garlic powder, pepper, and salt in a large mixing bowl.

Lightly flour a rolling pin and roll out dough out to about ¼ inch thickness. Use the lip of a cup to cut out 45 circles.

Remove chicken spinach dip from the refrigerator and fill each dough circle with 1 tablespoon of dip. Fold each circle in half and press down the edges to seal the dip inside the dough. Fold the left side and right side of each half circle towards each other like a fortune cookie.

Place the stuffed dough in an 11-inch nonstick or greased tart pan. Make an outer circle and work your way in, creating 4 circles total. Brush with egg wash.

Bake for 25 minutes, or until golden brown.