Preheat your oven to 350 F. Coat a standard bread pan with cooking spray and set aside.
Combine flour, baking powder, baking soda and salt. Set aside.
In a medium mixing bowl, whisk together the egg and melted butter. Add in brown sugar and milk and stir until combined. Stir in dry ingredients. (Dough will be thick.)
Scoop out about 1/2 cup of bread dough and place in a smaller bowl. Add 3 tsp cinnamon and stir dough until completely incorporated.
Stir in raisins and vanilla to the larger portion of dough.
Transfer dough to the bread pan by layering & alternating the non-cinnamon dough with drops of the cinnamon dough. I first spread some of the non-cinnamon dough, then put 2 dollops of cinnamon dough on top. Layer again, repeating the same process, then take a knife and run it through all the dough, swirling in the cinnamon mixture.
Bake at 350 degrees F for 60-65 minutes. Let cool for 30 minutes, then proceed with glaze instructions below.