Melt butter in 1/2 C. boiling water. Add flour; stir vigorously. Cook and stir until mixture forms a ball that doesn't separate. Remove from heat and cool slightly. Add egg and beat vigorously until smooth. Stir in grated cheese. Drop dough onto greased baking sheet, using 1 level tsp. dough for each puff. Bake at 400 degrees about 20 minutes.

Remove puffs from oven, cool and split. Combine tuna, cream cheese and milk; fill each puff with 2 tsp.

Yield: 24 puffs