Baking powder
Salt
Set aside.
Step 3: Cream Butter and Sugar
In a large bowl, beat butter and sugar together until light and fluffy, 3-4 minutes. This step is crucial for a tender crumb.
Step 4: Add Eggs and Vanilla
Add eggs one at a time, beating well after each addition. Beat in vanilla.
Step 5: Alternate Dry and Wet
With mixer on low, add the flour mixture in three additions, alternating with buttermilk in two additions, beginning and ending with flour. Mix just until combined—do not overmix.
Step 6: Bake
Pour batter into prepared pan and spread evenly. Bake for 45-55 minutes (for Bundt) or 35-40 minutes (for 9x13), until a toothpick inserted in the center comes out clean.
Step 7: Cool
Let cake cool in pan for 10-15 minutes, then turn out onto a wire rack to cool slightly. (The cake should still be warm when you add the sauce.)
Step 8: Make the Buttermilk Sauce
While cake cools, make the sauce:
In a small saucepan, combine butter, sugar, and buttermilk.
Bring to a boil over medium heat, stirring constantly.
Boil for 1-2 minutes, stirring, until slightly thickened.
Remove from heat and stir in vanilla and salt.
Step 9: Sauce the Cake
Place warm cake on a serving plate. Use a skewer or fork to poke holes all over the top. Slowly pour the warm buttermilk sauce over the cake, allowing it to soak in.
