Preheat oven to 350 degrees. Coat two 8" square baking pans with nonstick cooking spray, set aside. With a mixer at low speed, mix together the eggs, butter, milk and yogurt. Slowly add the dry cake mix and blend together one minute. Divide batter evenly between the two pans.
Bake cakes 20-25 minutes or until a toothpick inserted in the center comes out clean. Cool cakes 5 minutes, remove from pans and cool on a wire rack.
For frosting, in a separate bowl, cream together the butter and yogurt until creamy. Add the frosting mix and blend until smooth. Use your hands to break the cakes into large crumbs. Spoon about 2/3 of the frosting into the cake crumbs and mix until fully incorporated. Roll cake dough into tablespoon sized balls, then mold into a round ball shape. Freeze the cake balls for 15 minutes, or until firm. Remove cakes from the freezer. Microwave white chocolate in 15 second increments until melted and smooth.
Dip lollipop sticks into the melted chocolate and insert through the bottom of the cake balls. Dip the pops into the white chocolate and use a spoon to cover completely. Place in a cake pop holder or poke holes in an empty egg carton, to hold the cake pops. Decorate with sprinkles and remaining frosting.