Use a large saute pan to brown the bacon and onions over medium-high heat. This should take about 10 minutes and the onions should be soft and translucent. Allow to cool slightly and then drain the grease.
Combine the remaining ingredients in a large mixing bowl and then add the six eggs. Stir to combine well. Pour the mixture into a greased 9 x 13 baking pan.
If preparing as a make-ahead breakfast, wrap and seal the casserole and refrigerate overnight.
When ready to eat, bake at 350° F. for 35 minutes. Garnish with additional fresh herbs if desired.