You have egg whites left from making the pastry cream for your Boston Cream Pie (or any other recipe).
What to do?
You can freeze egg whites in a sealed container and use them later.
Or you can bake Marvelous Maple Meringues (invented by my daughter, these are a real bonus!):
Ingredients
Egg whites
1/4 TSP cream of tartar
1/2 cup maple syrup
parchment paper for baking
Instructions
Preheat the oven to 225°F.
Line a cookie sheet with parchment (cooking) paper.
Beat egg whites until frothy.
Add 1/4 tsp cream of tarter and beat until soft peaks form
Gradually beat in 1/2 cup maple syrup, and beat until stiff but not dry.
Use a pastry bag or drop by spoonfuls on the parchment paper on the cookie sheet.
Check after 1-1/2 hours. Bake for 1-1/2 to 2 hours, until lightly browned and dry. Use a spatula to remove one meringue from the parchment, let it cool for a few minutes, and taste. If it’s done (crisp, not spongy), turn the oven off and let the meringues cool completely in the oven.
Remove the meringues from the parchment with a spatula and store them in an airtight container—at least the ones you don’t eat right away!