"Overnight Croque Monsieur Casserole - Martin's Famous Potato Rolls and Bread..."
INGREDIENTS
•
1 Tablespoon Unsalted Butter, plus more to coat pan
1 Yellow Onion, roughly chopped (about 1 1/2 cups)
•
1 Tablespoon Unsalted Butter, plus more to coat pan
1 Yellow Onion, roughly chopped (about 1 1/2 cups)