When piped into a V shape, this chocolaty batter bakes into a heart for a Valentine's Day treat.
Pour whoopie-pie batter into a gallon-size resealable plastic bag (work in two batches). Snip a 1/2-inch hole in one corner of bag. Pipe Vs onto parchment-lined baking sheets, spaced 2 inches apart. Bake and cool. Thaw frozen raspberries in a sieve set over a bowl; press to extract 1/4 cup juice. Beat meringue into stiff, glossy peaks, then stir in juice. Transfer to another gallon-size resealable plastic bag. Snip a 1/2-inch hole in one corner. Pipe filling onto flat sides of half of cookies, then sandwich with remaining cookies.
To create perfect hearts, form the letter V: Start by piping a three-inch diagonal line downward. Pipe another one to meet it. (The tops are about three inches wide.)
Keep the bag stable while filling by placing it inside a tall container.