Line a 8x8 square baking dish with plastic wrap. Set aside.

In a heavy bottom saucepan, heat butter over medium-high heat.

When melted, add brown sugar and milk, stirring to combine. Bring to a simmer. When you start to see bubble, time about 3 minutes, stirring constantly. Mixture should be smooth. Do not overheat, it will seperate.

Remove from heat and whisk in peanut butter and vanilla.

Pour peanut butter mixture over powdered sugar in a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment. You will get the best results using an electric mixer versus hand mixing and pre-sifting your powdered sugar.

Mix until smooth, approximately 4 minutes.

Pour into prepared square baking dish. Pat mini chocolate chips into the top of half of the fudge.

Cover with plastic wrap and refrigerate until firm, approximately 8 hours.

Cut and serve. I prefer to keep my fudge chilled until ready to serve.