Preheat oven to 350 degrees. Mix ham, onion, cheese, egg, pepper and mustard. Stir to combine.

Spray mini-muffin pan with cooking spray. Unroll crescent rolls and press dough into one large rectangle. Cut rectangle into 24 pieces using a pizza cutter or knife. Place dough pieces in mini-muffin pans cups. Use a mini-tart shaper to form a cup (flour tart shaper after each use). Using a small scoop or spoon, divide filling evenly in each cup. Bake for 15 minutes or until lightly browned.