Whisk together first 2 ingredients in a medium saucepan; whisk in coconut water and sparkling beverage. Cook over medium-low heat 2 minutes, whisking just until sugar dissolves.
Remove from heat, and whisk in lemon juice.
Let stand 2 minutes.
Lightly grease a 12-cup muffin pan with cooking spray. Spoon 1/4 cup gelatin mixture into each cup of pan. Chill 4 hours or until completely set.
Gently run a small knife around the edges of each muffin cup, and invert a baking sheet over muffin pan. Holding baking sheet and pan together, invert and hold under hot running water until gelatin cakes unmold from muffin pan onto baking sheet.
Place 12 baking cups on a serving tray; place 1 cookie in each baking cup. Top each with a gelatin cake. Chill 1 to 2 hours.
Meanwhile, prepare Frosting: Process lavender and 1 cup sugar in a food processor 1 minute or until lavender is finely crushed.
Pour water to depth of 2 inches into bottom of a double boiler over medium-low heat; bring to a simmer.
Place egg whites, cream of tartar, and lavender mixture in top of double boiler over simmering water. Cook mixture, whisking constantly, 9 to 10 minutes or until a thermometer registers 16
Remove from heat, and beat at high speed with an electric mixer, using whisk attachment, 3 to 4 minutes or until stiff, glossy peaks form. Stir in vanilla.
Spoon frosting into a zip-top plastic freezer bag. (Do not seal.) Snip 1 corner of bag to make a small hole. Pipe frosting onto each gelatin cupcake.
Serve immediately.
*1 additional cup lemon-flavored sparkling beverage may substitute.
Note: Feel free to make these using a jumbo or mini muffin pan.
