Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with parchment paper, leaving an overhang on the sides for easy removal
In a medium mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and ground cinnamon until well combined. Set aside.
In a large mixing bowl, cream the softened butter and sugars until light and fluffy using an electric mixer.
Add the eggs, one at a time, to the butter-sugar mixture, mixing well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix on low speed until just combined. Set aside.
In a small bowl, combine the packed light brown sugar, all-purpose flour, cold butter pieces, and ground cinnamon for the cinnamon streusel topping. Use your fingers or a pastry cutter to blend the ingredients until they form a crumbly mixture.
Pour half the batter into the prepared loaf pan, spreading it out evenly. Top with half of the crumb mixture.
Add the rest of the batter in the pan and sprinkle the cinnamon streusel topping evenly over the bread batter.
Bake the bread in the preheated oven for 45-55 minutes, or until a toothpick inserted into the center comes out clean.
Once the bread is done baking, remove it from the oven and let it cool in the pan for 10 minutes. Then, carefully lift the bread out of the pan using the parchment paper overhang and transfer it to a wire rack to cool completely.
