Preheat oven to 425 degrees.
In a medium bowl, toss together sweet potatoes, onion, olive oil, seasoned pepper and 1/4 teaspoon salt. Spread in a single layer on a lightly greased jelly roll pan. Bake 15 minutes, or until sweet potatoes are just tender. Stir halfway through.They will get softer when the quiche is baking.
Let sweet potatoes cool to room temperature.
Remove pie crust from refrigerator and let sit on the counter for 5 minutes. Unroll the piecrust and fit into a pie plate or deep dish tart pan with removeable bottom. Trim excess pie crust from edges or fold excess and tuck it under. If tart pan has fluted edges, press the pie crust into the edges.
Line piecrust with a double layer of heavy duty aluminum foil. You can place pie weights or dried beans on top, but I found that a double thickness of heavy duty foil was enough by itself to keep the pie crust from puffing up while baking.
Place on a baking sheet and bake for 10 minutes. Remove foil and bake 5 more minutes. Let crust cool 5-10 minutes.
Reduce oven temperature to 350 degrees.
Add crumbled bacon to sweet potatoes and onions and place half of this mixture on top of piecrust. Top with half of cheese. Repeat layers.
Whisk together half-and-half, eggs, parsley, rosemary, salt and pepper and pour into piecrust. Bake in lower part of oven for 35 to 40 minutes or until set. Cool for 15 minutes before slicing.