Fry bacon until crisp, drain on paper towels, and reserve.

Place the parsnips in a saucepan of salted boiling water, and cook until soft. Drain parsnips, mash with 2 tablespoons of butter and season with salt and pepper. Add diced bacon. Wet your hands and shape the mixture into 6 cakes. Dip each cake into the flour, then the egg, then the bread crumbs to coat.

Heat the oil and remaining 2 tablespoons butter (or reserved bacon fat) in a large skillet. Fry the cakes until golden, 2 to 3 minutes per side.

Serve cakes immediately, sprinkled with crispy bacon.