Heat oven to 400°F Spray bottoms and sides of 3 (6-ounce) custard cups with baking spray with flour. Sprinkle 1 teaspoon cracker crumbs onto bottom and around side of each cup.
In 1-quart saucepan, melt butterscotch chips and butter over medium heat, stirring constantly. Remove from heat; cool slightly, about 5 minutes.
Meanwhile, in large bowl, beat whole eggs, egg yolks and rum extract with wire whisk or egg beater until well blended. Beat in brown sugar. Beat in melted butterscotch mixture and flour until well blended. Divide batter evenly among custard cups. Place cups on cookie sheet with sides.
Bake 13 to 16 minutes or until sides are set and centers are still soft (tops will be puffed and cracked). Let stand 5 minutes. Run small knife or metal spatula along sides of cakes to loosen. Immediately place individual dessert plate upside down over top of each cup; turn plate and cup over. Remove cup. Serve warm.