Combine all of the ingredients into a medium saucepan over medium low heat.
Bring to a simmer, about 10 minutes, stirring occasionally to incorporate all of the ingredients.
Once simmering, turn it down to the lowest setting your stove goes and allow it to thicken, anywhere from 5-10 minutes.
Once thickened, transfer to a container and refrigerate for at least an hour, but up to 3 days.
For the Cupcakes:
Preheat the oven to 350 degrees and line two cupcake pans with paper liners.
Add the dry boxed cake mix to the bowl of a stand mixer, along with eggs, milk, oil, extract and zest.
Mix for 2-3 minutes on low speed or until no lumps remain.
Divide batter into the prepared cupcake pans, filling each about ⅔ of the way full.
Bake for 18-21 minutes or until lightly golden. Remove from the oven and transfer cupcakes to a wire rack to cool completely.
Once cooled, use a sharp knife to cut a hole out of the top of each cupcake. Spoon the cooled blueberry compote into the center of each, about a teaspoon in each one.
For the Frosting:
Add the butter to the bowl of a stand mixer and beat on medium speed for 3 minutes.
Add in the powdered sugar, 1 cup at a time, waiting until each cup is fully incorporated before adding the next.
Add in 1 tablespoon of milk, the salt and the lemon extract and mix until combined. If the frosting is still thick, add the additional tablespoon of milk and more as needed until it reaches your desired consistency.
Transfer the frosting to a piping bag fitted with a large tip. Pipe frosting onto cupcakes and garnish the top of each with a fresh blueberry if desired.
Cupcakes could also be topped with yellow and/or blue sprinkles, lemon zest or a candied lemon in place of a blueberry.
Recipes on Cookaholic Wife are for information purposes only. Nutritional Data provided has not been evaluated by a nutritionist.