In a mixer, beat the butter and sugar until light and fully combined. Gradually add the eggs one at a time, beating well after each addition.
In one bowl, sift together the flour, baking soda, baking powder, and salt. In another bowl, whisk together the lemon curd, buttermilk, vanilla extract, and lemon zest.
With the mixer on low speed, alternately add the flour mixture and lemon curd mixture to the creamed butter and sugar, beginning and ending with the flour mixture. Mix just until combined after each addition.
Preheat the oven to 350°F. Grease and flour a bundt pan.
Pour the batter into the prepared bundt pan. Bake for 1 hour or until a toothpick inserted in the center comes out clean.
Allow the Grandma's Lemon Pound Cake to cool completely before removing from the pan. Serve topped with extra lemon curd.