Preheat oven to 350 degrees F.

In a small bowl, whisk together flour and baking soda and set aside.

In a mixing bowl, cream together butter and sugar until light and fluffy, about 3 minutes. Add the pudding mix and beat until well blended. Add eggs and vanilla and mix until just creamy. Slowly pour in the flour mixture and mix until just combined. Gently stir in fruity pebbles.

Scoop 1" balls and place on prepared cookie sheets. Bake for 8-10 minutes, or until just lightly browning (you don't want to overcook!). Let cool for 3 minutes on baking sheet, then transfer to wire rack to finish cooling. While cookies are cooling, prepare frosting.

For Milk Frosting, in a small pan over medium heat whisk flour into warm milk. Stir constantly until mixture becomes very thick and sticky, like a brownie batter. Take off heat and completely cool. Stir in vanilla.

While flour-milk mixture is cooling, cream together butter and sugar until very light and fluffy, about 6 minutes. Then add the completely cooled milk/flour/vanilla mixture and beat, beat, beat! If it looks separated, you haven’t beaten it enough! Beat it until it all combines and resembles whipped cream. Top on completely cooled cookies. Enjoy!