Preheat oven to 375 degrees F. Line a baking sheet with a Sil-Pat or parchment paper; set aside.

Heat a large skillet over medium-high heat. Add chicken to hot skillet and cook, stirring occasionally, until chicken is no longer pink, about 6 to 8 minutes.

Reduce heat to medium, and add spaghetti sauce to the chicken, stir, and cook until sauce is heated through. Remove from heat.

Open both cans of crescent rolls. Separate each roll into two halves and roll out each half, so that you have a long rectangle (made up of 4 crescent dough triangles. See images below.) Using your finger tips, pinch together all of the seams on each dough rectangle.

Place 1/4 of the chicken and sauce mixture on one half of each rectangle. Top chicken with about 2 tablespoons mozzarella. Fold the other half of the crescent dough on top of the chicken mixture, so that all edges line up and are even. Go around the edge of the dough rectangle and pinch the bottom dough edge over the top dough edge to seal the pocket. Repeat with remaining chicken, cheese, and dough.

Place each pocket on the prepared baking sheet. (If you're making these ahead of time, stop here!)

Sprinkle the top of each pocket with 1/8 teaspoon garlic powder, if desired, and about 1/4 cup mozzarella cheese.

Bake for about 18 to 22 minutes, until crescents are golden and cheese on top has melted and bubbled up. (Cooking time may increase if you're starting with cold pockets from the fridge or thawed.) Remove from oven and let cool for 2 to 3 minutes before serving.