Cook bacon slices in a 350 degree oven on a parchment lined baking sheet while preparing other ingredients. Check bacon after 20 minutes and remove to drain when thoroughly crisp.

Place pie crust into deep pie or quiche dish. Spread with mayonnaise [or mustard].

Meanwhile, put onion in skillet with butter and 1 T olive oil. Saute over medium low heat until they begin to turn golden, about 20 minutes. Put caramelized onion into pie shell. Put mushrooms in the skillet the onions were in and increase heat to medium high. Add a dash more olive oil if necessary. Saute mushrooms quickly until they release moisture and turn golden. Do this quickly so they don’t get rubbery. Add mushrooms to pie.

Cook asparagus crisp tender by wrapping in a kitchen towel and placing in the microwave for 2 minutes on high. Cut into 1 inch pieces.

Remove bacon from oven when done and drain well on paper towels. Cut into one inch pieces and add to pie along with asparagus. Top with Gruyere.

Beat eggs, add milk and seasonings. Pour over ingredients in pie shell and press ingredients down to submerge. You can add an extra egg and more milk if necessary.

Bake at 350 for 45-60 minutes. May be assembled ahead of time, covered and refrigerated. Add eggs and milk just before baking.

Makes 1 large deep dish pie, cut into wedges to serve.