Place the bowl and whisk attachment from a stand mixer into the freezer to chill.
Prepare the fruit:
Meanwhile, slice one or two 1-inch thick slices from the watermelon. Use a small star-shaped cookie cutter (mine is 2¾ inch) to cut out watermelon stars from the slices.
On a cutting board, use a sharp knife to carefully slice each star into 4 or 5 thinner stars - the thinner they are the more flexible they will be when placing them in the jars.
Make the cream:
Get the mixing bowl and whisk attachment from the freezer and assemble them on your stand mixer. Pour the whipping cream into the bowl and whip the cream on high speed. After the cream has been mixing for 3 minutes, turn it off and add in the confectioner's sugar and the vanilla.
Turn the mixer back on and beat the cream on high speed for another 2-3 minutes. Watch the cream carefully towards the last 2 minutes or so: you want the whipped cream to be stiff but if you overbeat it you will end up with vanilla-flavored butter!
Assemble the fools:
Place ¼ cup of whipped cream into the bottom of the mason jar or cup (a ¼-cup spring-loaded ice cream scoop works really for this.) Tap the jar a few times on the table to settle the whipped cream.
Hold the jar at an angle and place a watermelon star against the side of the glass. Still holding the jar at an angle, drop in 10-12 blueberries so that they layer against the watermelon slice. Then, place another watermelon star in the jar above the blueberries.
Hold the top watermelon slice against the glass with your finger and spoon or scoop in another ¼ cup of whipped cream: the cream should go over the blueberries and between the watermelon stars, so that the stars are visible from the outside of the jar. Tap the jar on the table a few times to settle the whipped cream.
Drop in 10-12 more blueberries on top of the cream. Top off the jar with one more watermelon star and one vanilla wafer cookie.
Serve immediately. (If you are preparing these in advance, hold off on the cookies. Cover the jars loosely with plastic wrap and refrigerate them. Top each with a cookie just before you serve them.)Makes 4 servings.
Get the freshest watermelon and blueberries you can find since they are the stars of these Fools! A ripe watermelon should feel heavy for its size, have a hollow sound when you knock on it, and have one yellow spot from where it was laying on the ground. Check the blueberries for stems and discard any shriveled ones.
The star cut-outs of watermelon for this recipe total 4 ounces, but in all likelihood you'll end up with a watermelon larger than 4 ounces! Just use what you need for this recipe, then slice up the rest to serve to your guests. Or stick the extra slices wrapped in the fridge for your family to snack on.
Before slicing the watermelon, take a little slice off the bottom of it so that it sits flat while you make the larger cuts.
If you don't want to use glass jars clear plastic cups would work, too. Make sure they're clear enough to see the watermelon stars through the sides.
To make these in advance layer the fruit and cream into the jars, cover them with plastic wrap and keep them in the fridge until you're ready to serve them - up to 8 hours in advance. Add the cookies to the top just before serving.
This dessert will work just fine with spray whipped cream if you need to substitute it - but you should really try making your own fresh batch! It's easy, quick, and really delicious.