Saute ground meat in 2 tbls. unsalted butter and 1 tbls. vegetable oil over medium-high heat until browned.
Add onions; cook until softened. Add minced garlic, sauteing only until you smell it.
Deglaze pan with sherry; cook until liquid evaporates.
Process meat mixture and remaining ingredients in food processor. Pulse until it resembles course sawdust. Do not overprocess.
Cook lasagna noodles al dente, according to package directions.
Spread a thin layer of filling (1 1/2 tbls.) over entire noodle. Loosely roll noodle and place seam side down in baking dish that has been lightly sauced on the bottom. Repeat until all mixture and noodles are used. Cover with bechamel and marinara.