Sausage and Three-Cheese Mac and Cheese - from Monica

1 BOX ELBOW MACARONI
2 TABLESPOONS OLIVE OIL
3/4 POUND ITALIAN SAUSAGE
1 SMALL YELLOW ONION
4 GLOVES GARLIC
3 TABLESPOONS FLOUR
1 CUP CHICKEN STOCK
3 CUPS MILK OR HALF-N-HALF
PINCH OF NUTMEG
1 1/2 CUPS GRATED ASIAGO CHEESE
2 CUPS GRATED PROVOLONE CHEESE
2 CUPS STUFFING BREAD CRUMBS (PEPPERIDGE FARMS)
4 TABLESPOONS BUTER, MELTED
1/2 CUPS GRATED PARMIGIANO REGGIANO
1/2 CUP FLAT LEAF PARSLEY - CHOPPED

PREHEAT BROILER ON HIGH - COOK PASTA ACCORDING TO BOX DIRECTIONS.
IN SKILLET, HEAT OLIVE OIL. ADD SAUSAGE AND BROWN, BREAKING IT UP INTO LITTLE PIECES. ONCE SAUSAGE IS BROWNED REMOVE FROM SKILLET.
DRAIN OFF THE FAT ALL BUT ABOUT 3 TABLESPOONS OF THE FAT. KEEP 3 TABLESPOONS OF THE FAT IN THE SKILLET AND ADD THE ONION AND GARLIC SEASON WITH SALT AND PEPPER. COOK UNITL ONIONS ARE SOFT. SPRINKLE ONIONS WITH FLOUR AND COOK ABOUT 1 MINUITE. WHISK IN CHICKEN STOCK AND MILK, BRING TO SIMMER AND SEASON WITH NUTMEG.
ADD ASIAGO, PROVOLONE CHEESE STIR UNITL MELTED. DRAIN PASTA, ADD COOKED PASTA AND SAUSAGE TO CHEESE SAUCE. TRANSFER TO BAKING DISH.
IN A BOWL COMBINE BREAD CRUMBS, MELTED BUTTER AND PARMIGIANO AND CHOPPED PARSLEY. TOSS TO COMBINE THEN SPRINKLE OVER MAC AND CHEESE IN BAKING DISH. TRANSFER BAKING DISH TO THE BROILER AND BROIL UNITL BREAD TOPPING IS NICE AND BROWN.