1In large bowl, mix peas, ham, cheese, onion, mayonnaise and mustard until well blended. Cover and refrigerate at least 2 hours.
2Heat oven to 400°F. Grease bottom and side of 9-inch glass pie plate. In 2-quart saucepan, heat water and butter to boiling. Add Bisquick mix all at once. Stir vigorously over low heat about 1 1/2 minutes or until mixture forms a ball; remove from heat.
3Beat in eggs, 1 at a time, with spoon; continue beating until smooth. Spread over bottom of pie plate (do not spread up side).
4Bake 35 to 40 minutes or until puffed and dry in center; cool. Just before serving, spoon filling into puff. Cut into wedges.