Feta Garlic Cheese Sauce

1/4 cup (half stick) butter
3 to 4 cloves garlic
1/4 cup flour
2 cups milk
1/2 tsp white pepper
1/2 tsp cayenne
1/2 tsp dried mustard powder
1/2 to 3/4 cup crumbled Feta cheese
1 egg yolk

Melt butter over medium heat.
Add smashed garlic and stir briefly.
Stir in flour and whisk for about two minutes to eliminate "floury" taste.
Slowly add milk, stirring constantly.
Bring to boil, stirring constantly to prevent sticking and scorching.
Add cheese in small handfuls and stir til melted.
Add spices.
Remove from heat.
With whisk, dip some sauce and add to the egg. (This prevents the egg from curdling). Return egg and cheese mixture to sauce.

Serve over pasta.