Preheat the oven to 350 degrees. Prepare two muffin tins with baking cups. Spritz the baking cups with nonstick cooking spray.
Mix the cake according to the package directions.
Using a large scoop, fill the cupcake liners two-thirds full.
Spoon one strawberry and about ½ teaspoon of the pie filling jelly into the middle of each cupcake. Swirl slightly with a toothpick or knife.
Bake the cupcakes for 20 to 22 minutes or until a toothpick in the center returns clean. Place the muffin tins on a wire rack to cool for 10 minutes prior to removing the cupcakes to cool completely.
To make the frosting: To the powdered sugar, stir in the salt and set aside. Beat the butter on high for 3 to 5 minutes or until creamy and light in color. Mix in the vanilla. Add the sugars and whipping cream, beating on low until the sugar is incorporated and then switching to high speed and scraping down the sides as needed. Beat the frosting until fluffy, about 5 minutes. Stir slightly to remove air pockets.
Transfer the icing into a decorating bag with a star tip and frost with a circular pattern around each cupcake.
To make the glass: Prepare a large, rimmed baking sheet with parchment paper. In a large saucepan, stir together the water, corn syrup, sugar, and cream of tartar. Place over medium-high heat and while stirring constantly bring the mixture to a boil. Continue boiling the mixture until it reaches 300 degrees, or hard ball stage.
Immediately pour the syrup onto the prepared baking sheet. Exercise caution when moving the baking sheet as it will be hot. Allow the syrup to cool completely into a solid.
Then, strike the candy with the back of a metal spoon or butterknife to crack into large shards.
Press the shards of candy glass into the cupcakes and then drizzle with the strawberry pie filling gel.
Refrigerate until ready to serve. Best if served within 8 hours.