1. Preheat your oven to 350 degrees.
2. Into your stand mixer or large mixing bowl, place the cake mix, flour and pudding mix. Toss to combine.
3. Add the oil, water, vanilla, sour cream and egg whites. Mix for 1 minute on medium speed, then scrape the bottom of the bowl with a rubber spatula and mix on medium speed for 2 minutes, or until the batter is thick and glossy.
4. Line your muffin tins with cupcake liners and spray with cooking spray. Fill the liners a little bit less than 2/3 full of batter.
5. Bake for 15-18 minutes, or until the tops of the cupcakes spring back when lightly tapped.
6. Remove the pans from the oven and allow them to rest for 5 minutes. Remove the cupcakes to a wire rack to cool completely.
7. To make the filling, place the white chocolate pudding mix and half and half into your stand mixer. Beat on medium speed (with the whisk attachment) for 1 minute. Scrape the bottom of the bowl with a rubber spatula and beat for an additional 2-3 minutes or until the mixture thickens. Cover and refrigerate for 15 minutes.
8. When the cupcakes are completely cool, pipe the filling into each cupcake using a cake decorating bag and large tip (see picture below).
9. To make the frosting, melt the white chocolate chips in the microwave in 30 second intervals, stirring after each one, until the chocolate is melted. (Should only take about 1 1/2 minutes). Set aside for 5 minutes.
10. Place the softened butter into your stand mixer and mix until smooth.
11. Add the powdered sugar and half and half and mix for 30 seconds or so (just enough to get things started, but not fully mixed). Add the melted white chocolate and mix for 1-2 minutes.
12. Add the jam, vanilla, food coloring and salt. Mix on medium speed for 2-3 minutes or until light and fluffy.
13. Pipe the frosting onto the cupcakes.
14. Press a fresh strawberry on top.
Store in the fridge until you are ready to serve.