Preheat the oven to 350ºF. Spray or butter and flour one large 10 or 12-cup Bundt pan.

In a medium bowl, sift together the flour, baking powder and salt. Set aside.

In the bowl of a stand mixer or with an electric mixer, cream together butter, coconut oil and sugar until light and fluffy, about 3-4 minutes. Look for the mixture to stick to the sides of the bowl. Add eggs one at a time, beating well after each addition. Stop the mixer and scrape the bottom and sides of the bowl. Add vanilla and mix until incorporated.

In a measuring cup, whisk together buttermilk and sour cream. Add dry ingredients in three additions to butter mixture alternately with buttermilk mixture, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in lemon juice and lemon zest.

Pour batter into prepared pan. Bake cake until a toothpick inserted into the cake comes out clean, about 55 minutes. Check the cake after 40 minutes or so. If the top is beginning to get very brown, tent aluminum foil over top of the cake to prevent burning or over browning.

Remove the cake from the oven and cool in the pan for 15 minutes. Place an inverted wire cooling rack over top of the cake. Using oven mitts, grasp the sides of the bundt and the sides of the wire rack and carefully but swiftly overturn the cake onto the wire rack. Lift the bundt pan off the cake and allow the cake to cool completely.

Prepare the glaze by whisking together all ingredients in a medium bowl. Drizzle over the cooled cake.