Remove the pastry dough from the refrigerator and fold a few times. Roll the dough out on a floured surface into a rectangle about 12 x 18 inches with the long side facing you.
Place the butter and peanut butter in a microwaveable bowl and microwave on high for about 90 seconds, stopping to stir halfway through. After 90 seconds, stir until smooth then stir in the vanilla and milk. Stir in the powdered sugar then microwave on high another 90 seconds, stirring halfway through.
Save half of the peanut butter filling back to use as topping. Using the other half of filling, spread the peanut butter fudge evenly over the pastry rectangle, coming to 1⁄2" of the edge. Allow the filling to sit on the rectangle a few minutes to firm up then roll the rectangle up from the long side to form an 18" long log. Cut the log crosswise into twelve 1 1⁄2" wide pieces and place in a 9 x 13" baking pan or jumbo muffin tins sprayed with nonstick spray. Cover and allow to rise at room temperature for 30-45 minutes or place in the refrigerator overnight.