Oven 350. Grease a 9 inch round cake pan. Heat butter and cream in a small pot till butter melts, and cool. Beat eggs, sugar, and salt with a mixer on high speed for 5 minutes (until thick and pale) or 12 minutes with a handheld, next add zest, baking powder, and vanillas and mix on low until combined. Add 1.25 cups flour and half of the butter mixture and mix on low till just blended, then repeat with remaining flour and butter. Increase speed to medium and beat for 1 minutes until the batter is thick and sticky. Spread into the prepared pan and bake until cake is springy to the touch (40 minutes). Cool completely on a rack.
Slice cake in half and spread with whipped cream (1 pint whipped with 1 tbsp sugar) and sliced strawberries, blueberries, raspberries or all 3! Replace top half and sift confectioner's sugar over all. Chill till ready to serve.