Preheat oven to 350°F and line a standard twelve muffin pan with paper liners; set aside.
To make the streusel, in a medium bowl, combine the flour, sugar, cinnamon and salt. Add the butter and rub it in with your fingers until it resembles coarse crumbs. Stir in the bacon and set aside until ready to use.
To make the muffins, in a large bowl, whisk together the flour, sugar, baking powder and salt. In a separate bowl, mash the bananas. Whisk in the peanut butter, butter, eggs, buttermilk and vanilla until somewhat smooth. Add the wet ingredients into the dry and fold gently with a rubber spatula until just incorporated. Do not over mix at this stage. Fold in the peanut butter chips if using.
Divide the batter evenly among the prepared pan and top each muffin generously with the bacon streusel. Bake until golden brown and a toothpick, inserted in the middle, comes out clean, about 18 to 20 minutes. Remove from the oven and let cool before serving.