Think these desserts look yummy, then rest assured they are no big whoop(ie) to make!  To start out, I purchased a heart shaped baking pan from Wilton (found at Target) because no way was I going to cut out individual hearts!  
To make life even more simple, I used a boxed cake mix for the cake, though I could have used the recipe that came with the pan.  I then used the pan instructions for the filling:

6 oz butter, softened
1 1/2 cups of confectioner's sugar, sifted
1 jar (7 oz) marshmallow fluff/creme
1/8 tsp salt

1. Whip butter with an electric mixer until creamy
2. Add sugar and salt to the mixture and beat until smooth
3. Add marshmallow fluff and vanilla, mix until combined

I decorated it with a little valentine color confetti, rolling the sides and pressing the confetti into the filling.  There it is!  All done!  Now time to get a sugar rush and whoop(ie) it up!