Cool 10 minutes. Prep Time 20 minutes. 1 pkg Fresh Blackberries (frozen is ok) (170 g / 6 oz) 2 3/4 + 1 TBS Cups AP Flour (338 g / 12 oz) It’s a delicious summer cake perfect for any celebration or gathering. Invert cakes from pans onto rack to cool. Keyword baking science, blackeberry dessert, blackeberry pound cake, lemon blackberry, lemon pound cake . Spread each top (which is actually the flat bottom sides)with blackberry jam while cake is still hot. Bake cake according to directions on box making an 8 or 9" layer cake, adding the dry lemon pudding mix and lemon juice. Blackberry lemon cake is a moist three-layer vanilla white cake with lemon cream filling and blackberry buttercream. Servings 1 Bundt Cake. Author One Sarcastic Baker. Cook Time 45 minutes. Ingredients. Use 1/3-1/2 cup per cake… Summer gatherings call for seasonal summer desserts.