For the cake:
For the frosting:
1. Preheat oven to 350F (180C). Butter two 8-inch (20cm) round cake pans, line with parchment paper, and butter the parchment. Set aside.
2. Sift flour and baking powder into a large bowl. Add salt, puppy seeds and stir. Set aside.
3. In a large bowl beat butter and sugar, beat until creamy and pale. Add oil and beat until incorporated. Add vanilla extract, lemon juice and lemon zest, beat until incorporated. Add eggs, one at the time, beating just until combined after each addition.
4. Add 1/3 of the flour mixture to the butter mixture. Beat on low speed just until combined. Add 1/2 of the buttermilk and beat just until combined. Add another 1/3 of the flour mixture and beat just until combined. Beat the remaining buttermilk, add the remaining flour mixture and mix just until combined.
5. Divide batter evenly between prepared pans. Bake for 35-40 minutes, until a toothpick inserted in the center of the cake comes out clean. Allow to cool 10 minutes in the pans, release from the pans and let cool completely.
6. Make the frosting: in a large bowl, beat cream cheese with powdered sugar and vanilla extract. Beat until smooth and creamy. In a separate bowl beat heavy cream to stiff peaks. Fold 1/3 of the whipped cream into the cream cheese mixture, then fold the remaining whipped cream.
7. Assemble the cake: cut the top of the cakes, place one cake layer with flat side down. Spread a layer of frosting, place the second layer of cake on top of the frosting, flat side up. Spread evenly the frosting on top and sides of the cake. Refrigerate for at least 2 hours.
8. Decorate with poppy seeds and lemon zest.