Preheat the oven to 350 degrees Fahrenheit. Spray the insides of 24 four-ounce jars with canola oil.

Sift together the flour, sugar, baking powder, and salt in a large bowl. Add the butter and strawberry puree, and beat, starting slowly and then more quickly, for two to three minutes, until you have a very thick batter.

In a separate bowl, beat the egg whites until frothy, then whisk in the milk.

Add one-third cup of the egg white mixture to the batter, then beat until incorporated. Repeat until all the egg white mixture is incorporated. Be sure to scrape down the sides of the bowl as you go. When all the egg white mixture has been added, set the batter aside.

Sift together the flour, baking powder, and salt in a large bowl and set aside.

In another large bowl, cream the butter and sugar until smooth. Beat in the eggs, one at a time.

In a separate bowl, combine the milk and cream.

Stir one-third cup of the milk mixture into the butter mixture, and then stir one-third cup of the flour mixture into the butter mixture. Continue alternating additions of milk and flour until they are fully incorporated into the batter. Stir in the vanilla.

Divide the batter between two bowls. In a small bowl, mix together the hot coffee and the cocoa, and add this mixture to one of the bowls, creating the chocolate cake batter.

Layering the flavors one at a time, scoop or spoon two tablespoons of each of the three cake batters into each of the prepared jars.

Place the jars two inches apart on a large baking sheet. Bake for 20 to 25 minutes, until the centers of the cakes spring back when touched. Remove the cakes from the oven and let them cool completely.

While the cakes are baking, make the frosting. Cream the butter, add the confectioners’ sugar, and beat thoroughly. Beat in two tablespoons of the heavy cream.

Divide the frosting into thirds. Add the strawberry puree to one third and mix in. Beat the bittersweet chocolate into the second third and the vanilla extract into the final third. Add a teaspoon or two of additional heavy cream to the buttercream frostings, if needed, for a smooth consistency.

Transfer the three frostings to three piping bags. Cut the tips off to create a half-inch opening, and then place the three bags into one larger pastry bag fitted with a large star tip. Pipe the frosting onto the cooled cakes in a swirl shape before serving.