Follow directions on the cake mix package to make cupcakes, but don't use cupcake papers when baking.
In a food processor, combine marscapone, strawberries, 1/4 cup sugar, and lemon juice. Process until smooth.
Transfer to a pastry bag with small tip. When the cupcakes have cooled, insert the tip of the pastry bag into the bottom of a cupcake and squeeze the mixture into the cupcake until it plumps slightly. Continue with remaining cupcakes.
In small saucepan bring 1/2 cup sugar, water, and vanilla to a simmer over medium heat. Simmer until sugar dissolves.
In medium bowl combine sugar/water/vanilla mixture with the confectioners sugar. Stir until smooth.
Working quickly use a rubber spatula to spread the icing on the top of the cupcakes. If the icing begins to firm up in the bowl, pop it in the microwave for a few seconds to soften.