Rough chop cauliflower. Add it to a food processor along with rosemary and thyme. Pulse until finely chopped and resembling bread crumbs.
To trim leeks, cut off white bottoms and green tops. Slice lengthwise and then cut into 1/2 inch pieces. Then soak pieces in a bowl of cold water to remove dirt. Drain well.
To prepare lemon, use a sharp paring knife to cut the lemon in half. Slice into thin pieces and remove the seeds. Chop lemon into 1/2 inch size pieces.
Heat 3/4 cup of olive oil in large braising pan. Add drained leeks, cauliflower mixture and chopped lemon. Sautee well on medium high heat for about 20 minutes. Add stock and bacon grease and cover. Bake covered in 350 degree oven for 50 min. Be sure to check on it a few times to stir it.