Preheat the oven to 350 degrees. Grease and flour a Garland Bundt pan.
In a large bowl, mix together the brown sugar, margarine and peanut butter until mixed well. Beat in the eggs one at a time, then stir in the vanilla. Combine the flour, baking powder and baking soda; stir into the batter alternately with the milk. Spoon into the prepared Bundt pan.
Bake for 20 – 30 minutes in the preheated oven, until a toothpick inserted into the cake comes out clean. Cool in the pan for at least 10 minutes before removing to a wire rack to cool completely.
To make the chocolate ganache:
Put the heavy whipping cream in a medium saucepan over medium heat. Bring to a boil, stirring occasionally. Meanwhile, place the chocolate chips in a large stainless steel mixing bowl. Remove the cream from the heat and pour it over the chocolate chips. Stir until the chocolate has melted. Let sit about 30 minutes until it thickens. Pour over the mini Bundt cakes to cover them. Garnish with store bought or homemade buckeye candies, if desired.
Serving size: 12 mini Bundt cakes - 1 cake per serving.