Slice the pound cake into even slices. Use a circle cutter to cut out a circle from each slice.: The kitchen will smell faintly of butter as you cut through the soft crumb of the pound cake , and a clean, smooth edge shows the cake held its shape. Gently press the circle cutter straight down without twisting to avoid tearing. If your slices are uneven, chill the cake for ten to fifteen minutes so it firms up, then slice to get uniform thickness. A common mistake is cutting while the cake is warm which makes shapes sloppy; cool first for the neatest results.
Beat the heavy cream in a chilled bowl just until soft peaks form. Add in vanilla and sugar and continue beating until stiff peaks form.: You will hear a subtle change in sound from thin splashes to thicker, velvety swirls as the heavy cream thickens, and the bowl will begin to hold its shape when you lift the whisk. Start slow then increase speed, and watch for soft peaks that gently fold over, then firm peaks that stand tall. The vanilla and powdered sugar should be sifted or added gradually so they dissolve fully. Stop before the cream starts to look grainy or buttery; over whipping will lead to separation. If you do over whip, a small splash of fresh heavy cream and gentle folding can rescue it.
Spread a layer of whipped cream on one pound cake and layer with blueberries and/or strawberries. Add another slice of pound cake and repeat.: As you spread, notice the contrast between the pale, glossy whipped heavy cream and the golden crumb of the pound cake . Use an offset spatula or the back of a spoon to create an even layer about one quarter inch thick, then dot the surface with a scattering of fresh blueberries or thin slices of fresh strawberries . The fruit will release a little juice as you layer, which melds into the cream and adds bright flavor. Stack gently so the cakes do not slide; a slight pressing motion helps the layers adhere. Avoid piling too much cream in a single layer which can make the cakes top heavy and prone to slipping.
Use the blueberries and strawberries to create a design on top if you desire.: The final plating is where personality shines, and arranging fresh blueberries and fresh strawberries into a motif gives each cake its own character. You might form concentric circles, a star, or a striped pattern, placing fruit with a small gap between pieces so the whipped heavy cream peeks through. Visual balance is key, so step back and adjust spacing as needed. One frequent misstep is overcrowding the top which hides the cream and makes each bite overly fruity; aim for striking, not smothered.
