Butter 8 4x2 1/2 - inch ramekins and place in a shallow roasting pan. Set aside. Preheat oven to 350 degrees.
In a medium sauce pan, melt butter, add flour stirring well. Slowly whisk in half and half. Cook 2 minutes or so until thickened and smooth. Add cheeses and stir until melted.
Remove from heat and whisk in egg yolks, one at a time. Season generously with salt and pepper (slighty overseason)
Using a mixer, beat egg whites and cream of tartar until soft peaks. Stir in 1/4th of the egg whites into cheese mixture to lighten then carefully fold in remaining egg whites. Don't overdo.. Divide the mixture among the 8 ramekins, filling each to 1/4" of the top. Place in roasting pan. Pour hot to boiling water to the pan coming 1/2-3/4 cup sides of ramekins. Bake 40 -45 minutes, until tops are set and brown.
Remove from water bath and allow to cool to room temperature. They will fall...that's ok. At this point, the pudding soufflés can be covered and refrigerated for up to 2 days. They will puff right back up upon second baking.