Heat oven to 375°F. Make mac & cheese as directed on box. Stir in mustard until well blended. Stir in peas, carrots and 1/2 cup of the cheese.
Meanwhile, separate dough into 5 biscuits; separate each biscuit into 2 layers. Firmly press 1 biscuit layer in bottom and up side of each of 10 ungreased regular-size muffin cups, forming 1/4-inch rim. Fill with macaroni mixture; sprinkle with remaining 1/4 cup cheese.
Bake 16 to 20 minutes or until edges of biscuits are golden brown. Cool 1 minute; remove from pan.