Bake 10-inch pie crusts to directions. Place pie crusts on a wire rack to cool and reduce oven to 325°F.
Heat a saute pan with olive oil. Add sausage, onion and serrano pepper. Season with 1/4-teaspoon sea salt and 1/4-teaspoon white pepper. Saute until sausage is brown. Remove sausage and place on a paper towel.
Spread spicy brown mustard over bottom pie crust. Spread grated asiago cheese over mustard. Add sausage, onion, pepper over cheese and press sausage mixture lightly into the cheese.
In a bowl wisk together eggs, salt and white pepper. In a saucepan add heavy cream, nutmeg, cream fraiche and whisk until cream is warm. Wisk warm cream and herbs into eggs.
Pour egg mixture into pie crust and place on a sheet pan.
Bake at 325 F 35-40 minutes or till a knife inserted into center comes out clean. Remove Quich and place on a rack to cool for 10-minutes before serving.