Step 1

Sprinkle ground beef with seasoned salt and pepper. Pulse mushrooms in a food processor until finely chopped. Add to seasoned beef, mixing lightly but thoroughly. Shape into four 1/2-in.-thick patties.

Step 2

In a large skillet, heat 2 tablespoons butter over medium heat. Add burgers; cook 6-8 minutes on each side, basting with butter, until a thermometer reads 160°. Remove from heat; keep warm. Add bun tops to skillet; toast until golden brown.

Step 3

Transfer burgers to bun bottoms. Top each with 1 teaspoon butter. Replace bun tops. Serve with toppings.