For the cookies and frosting, please follow the directions at the links above.

For the cake:

1. Preheat oven to 350°F. In a mixing bowl, cream together the softened butter and brown sugar. Add the eggs one at a time, beating well after each one. Add vanilla. In a separate bowl, mix together the flour, baking powder, baking soda and salt. Alternate adding the dry ingredients and the milk to the batter - beginning and ending with the dry ingredients.
2. Let me pause here to say I have no idea why that's important.. alternating adding it in, beginning and ending with the dry ingredients... but I did it anyway, just in case it mattered!
3. Okay, on with the cake. Divide the batter between (2) prepared 8 or 9 inch pans. I prepare my pans with homemade cake release, FYI. Bake for 25-30 minutes, or until toothpick inserted into center comes out clean. Cool for 10 minutes in the pan, flip out onto a wire rack and allow to cool completely.

For the filling:

1. Cream together the butter and brown sugar for about 2 minutes. Add in the vanilla, then flour, and then the sweetened condensed milk. Resist the urge to eat the rest of the condensed milk with a spoon! Gently stir in the mini chocolate chips. Now at this point, you could just spread this on one layer of the cake and spread it out, then put on the top layer - but this filling is a bit squishy and I was afraid it would run out the sides, so I made a dam of frosting on the edges (like here) and then filled in the middle!
2. Frost the cake and then used the cookies and/or chocolate chips to make it pretty! Enjoy!!