You can put this all together through step two a day ahead. Cover and refrigerate. The next day, just plan on baking for 50 minutes or so.
- In 6-quart pan over medium-high heat, stir bacon often until browned and crisp, 6 to 8 minutes.
- Remove to paper towel and drain all but 1 1/2 tablespoons fat in pan.
- Add onions to pan and stir often until they begin to brown and stick to bottom of pan, 7 to 9 minutes.
- Add beans and their liquid, catsup, brown sugar, dry mustard,and cooked bacon; mix well.
- Pour into a shallow 3-quart casserole.
- Bake beans, uncovered, in a 350°F oven until they are bubbling in the center, 30 to 40 minutes.
- Serve hot.