Hot Tuna Mousse With Cheddar Cheese Sauce

In large bowl of electric mixer, let egg whites warm to room temperature--about 1 hour.

Meanwhile, preheat oven to 350 degrees F. Grease a 1 1/2-quart mold or casserole.

Combine tuna, sour cream, salt, pepper, mustard, and Worcestershire. Beat egg whites until stiff peaks form when beater is raised. With rubber scraper, gently fold tuna mixture into egg whites just until combined.

Turn mixture into prepared mold or casserole. Bake 40 minutes, or until mousse feels firm when surface is gently pressed with fingertip.

Meanwhile, make sauce: Slowly melt butter in medium saucepan. Remove from heat. Add flour, stirring to make a smooth paste. Gradually add milk, stirring, then add salt, pepper, and mustard.

Bring to boiling, stirring. Reduce heat, simmer 1 minute. Add cheese, cook, stirring, until cheese melts.

To serve: Run a spatula around edge of mold, invert onto serving platter, unmold. Pour sauce over top, garnish with parsley sprigs.