Preheat oven to 350 degrees with the rack in the center. Prepare a 10 or 12 cup Bundt pan by generously spraying with cooking spray or coating with shortening and dusting with flour.
Beat butter and sugar using an electric mixer for 3 to 5 minutes, until light and fluffy. The color of the butter will change when it has been beaten enough. Add the eggs, one at a time, and beat each in until well combined.
Combine the flour, baking powder, and salt in a separate large mixing bowl. Add to the butter mixture, alternating with the milk, one third at a time, mixing on low until just combined. Do not overbeat. Stir in the lemon juice and lemon zest by hand.
Pour the cake batter into the pan and smooth the top.
Bake for 45-55 minutes until a cake tester inserted into the center comes out clean. Allow the cake to cool in the pan for about 10 minutes, then carefully flip onto a wire cooling rack to cool for 20 minutes.
Pour lemon curd on top on warm cake spreading gently with pastry brush or spatula.
Pound cake will keep well at room temperature, covered for about 3 days. For longer storage, allow it to fully cool and wrap it tightly. Freeze for up to one month.