Bean Rarebit

¼ cup butter

¼ cup chopped onion

¼ cup all-purpose flour

½ teaspoon salt

2 cups milk

1 teaspoon Dijon mustard

2 cups shredded Cheddar cheese

1 (15.5 ounce) can white beans, drained and rinsed

Melt butter in a saucepan over medium heat. Cook and stir onion until soft, about 5 minutes.

Stir flour and salt into onion until flour forms a paste, 1 to 2 minutes.

Gradually whisk milk and Dijon mustard into onion mixture and bring to a simmer, whisking constantly until the sauce thickens, 5 to 7 minutes.

Stir Cheddar cheese and white beans into sauce until cheese melts into sauce, 5 to 7 minutes.