Lucinda prepares a simple red, white, and blue layer cake decorated with raspberries and blueberries.
Line the sides of a 9"x3" springform pan with parchment paper strips. Lay half the vanilla wafers on the bottom of the pan in overlapping concentric circles.
Puree strawberries in a food processor. In a large bowl or stand mixer, whisk whipped cream and sugar to soft peaks. Remove 2/3 of the whipped cream from the bowl. Fold the strawberry puree into the remaining 1/3 whipped cream.
Put 1 cup plain whipped cream into a large resealable plastic bag. Snip off one corner of the bag. Pipe the cream over the wafers, along the sides of the pan, to create a one-inch dam. Pour the strawberry whipped cream into the center of the pan and spread the edges to the dam.
Place the remaining cookies over the cream. Top the cookies with the remaining cream, spread to the edges of the pan, and smooth to level. Place the blueberries evenly over one third of the cream. Place the raspberries in four or five stripes to create a flag pattern.
Chill at least 8 hours or up to overnight. Remove the sides of the springform pan and the parchment. Cut cake into wedges and serve.