Baking the mini cookies and creme cupcakes:
Preheat the oven to 350 degrees. Line 2 mini cupcake pans with 36 mini baking cups.
Sift together the flour, baking powder and salt in a bowl, and set aside.
Place the unsalted butter in the bowl of a stand mixer or hand-held electric mixer. Add the sugar; beat on medium speed until well incorporated.
Add the eggs one at a time, mixing slowly after each addition.
Combine the vanilla extract and milk in a large liquid measuring cup.
Reduce the speed to low. Add one-third of the flour mixture to the butter mixture, then gradually add one-third of the milk mixture, beating until well incorporated. Add another one-third of the flour mixture, followed by one-third of the milk mixture. Add the remaining flour mixture, followed by the remaining milk mixture, and beat just until combined.
Gently fold in the crushed Oreo cookie crumble, just until incorporated.
Scoop batter into baking cups and bake for 10 minutes or until a toothpick inserted into the center of a cupcake comes out clean. Transfer the pan to a wire rack to cool completely.
Making the "grass" green buttercream frosting:
Place all the ingredients in the bowl of a stand mixer or hand-held electric mixer. Beat on medium speed until well incorporated. Then, beat on high speed for 1-2 minutes, until light and fluffy. Place frosting in a disposable piping bag fitted with a multi-opening "grass" tip.
Making the chocolate ganache:
Fill a medium saucepan with an inch or two of water and place over medium-low heat. Place the chocolate chips in a medium glass bowl over the saucepan and melt the chocolate chips. Stir occasionally until the chips are completely melted. Remove the bowl of melted chocolate from the saucepan.
Making the fondant baseballs:
Take 1 tsp of white fondant and roll into the size of a gumball to form the "baseball". Take ½ tsp of red fondant and roll between your fingers to make a long thin strip. Cut strip in half and lay one half on top and bottom of baseball. Repeat to make a total of 24 baseballs.
Decorating the cupcakes and serving:
Dip each cupcake into the chocolate ganache so that the top of the cupcake is completely covered. Then, dip each cupcake into the bowl of Oreo cookie crumble so that the cupcake is completely covered in Oreo "dirt". Pipe a patch of green grass buttercream on 12 cupcakes. Place a fondant baseball on remaining 24 cupcakes.
To serve, place 4 mini cupcakes in each cupcake tray (3 cupcakes with baseballs and 1 cupcake with the green grass buttercream patch). Serve and enjoy!