Separate or cut dough into 4 long rectangles (if using crescent rolls, press perforations to seal). Cut each rectangle in half; press into 3 1/2-inch squares.
Spoon peanut butter in center of each square; top with 2-3 banana slices. Fold dough over filling; press edges with fork to seal. Brush with egg; sprinkle with sunflower nuts.
Bake at 375°F 12 to 16 minutes.