Heat oven to 350 degrees F. Grease and flour 2 (9-inch) nonstick cake pans.
Place cake mix, milk, butter, eggs and vanilla extract in bowl of electric mixer. Beat on medium speed 3 minutes.
Toss toffee bits with flour in small dish; fold into cake batter.
Divide batter between pans; smooth tops with rubber spatula.
Bake until cake is set and springs back when lightly touched in center, about 30 minutes.
Let cool on wire rack for 10 minutes.
Run knife around pan edges. Remove from pans; let cool completely before frosting.
Whipped Cream Frosting
Refrigerate bowl of electric mixer and beaters about 15 minutes.
Pour water in glass measuring cup; sprinkle gelatine over water. Let stand for 2 minutes.
Microwave on HIGH for 30 seconds. Stir thoroughly; let stand until gelatine is completely dissolved, about 2 minutes.
Beat cream and sugar in bowl of electric mixer on medium speed. As cream just begins to thicken, add cooled gelatine mixture. Beat until cream is thickened.
Beat in vanilla extract.
Fold in crushed toffee.
Split cake layers in half horizontally, using serrated knife. Place 1 layer, cut side up, on serving platter. Brush off crumbs. Spread layer with 1/4-inch layer of frosting. Top with another cake layer.
Repeat with remaining frosting and layers.
Frost top and sides of cake.
Garnish sides of cake with milk chocolate toffee bits.
* 18.25 ounce boxes of cake mix have been replaced by 16 ounce boxes. To compensate for the volume loss, whisk 6 tablespoons all-purpose flour into the dry cake mix before proceeding with the recipe.
** We used Heath brand toffee bits
*** Gelatine added to whipped cream gives it a firmer, mousse-like texture and keeps liquid from separating. It also holds up longer.
Betty Crocker discontinued its butter brickle cake mix and frosting mix in 1990, but fans can re-create the flavors. General Mills, which manufactured the mixes, suggested using its yellow, butter yellow, golden vanilla or French vanilla cake mix and folding in 1/2 cup of butter brickle pieces.
You can make the cake mix according to the package instructions or follow a suggestion from Anne Byrn, author of "The Cake Mix Doctor": She recommends using melted butter instead of oil and adding flavoring extract, such as vanilla, to hide
the "cake mix flavor." We did both, and the tricks were effective.
General Mills didn't have a solution for duplicating the frosting, so we've provided a delicious alternative.