Ingredients
- 3 cups cake flour
- 1 tbs. baking powder
- 3/4 tsp. salt
- 6 tbs. unsalted butter at room temp
- 1 tbs. pure vanilla extract
- 2 cups sugar
- 1/2 cup oil
- 3 large eggs + 4 egg yolks, at room temp
- 1 cup buttermilk at room temp
Preparation
Step 1
Position rack in lower third of oven, preheat to 325 degrees, and prepare 12 cup bundt pan with cooking spray and flour. (I use Baker's Joy.)
Sift flour, baking powder, and salt into large bowl.
In bowl of stand mixer beat butter and vanilla on medium speed until smooth and creamy. Add sugar until evenly mixed, about 1 minute. Slowly pour in oil and beat until light and fluffy, about 2 minutes. Add eggs and egg yolks one at a time, beating well after each addition.
Reduce mixer speed to low. Stir in flour mixture and buttermilk in three alternate additions, ending with the buttermilk, and continue to mix until batter is smooth and no lumps remain.
Turn off mixer, fold batter several times by hand, and pour into prepared pan.
Bake for 60-70 minutes until cake is golden and tests done; let cool for 2 hours.
For the filling:
1 7.5 oz. jar marshmallow cream
1/2 cup unsalted butter at room temp
1 tsp. pure vanilla extract
Beat ingredients together in large stand mixer; transfer to pastry bag with large round tip.
With cake still in pan, use paring knife or apple corer to cut 6-7 deep holes in bottom of cake, each about 3/4" in diameter, being careful not to cut through top of cake.
Discard (i.e., nibble) cake scraps. With your fingers, gently burrow horizontal tunnel around center of cake, connecting vertical holes.
Insert tip of pastry bag into each hole and squeeze in filling, tilting pastry bag back and forth as you work to encourage filling into horizontal tunnel through the cake. When cake is filled, use spatula to clear away extra filling from bottom of cake.
Quickly and carefully invert cake onto a serving platter; sprinkle with powered sugar if desired.