Preheat oven to 350 F / 177 C. Line two regular size bread pans with parchment and spray lightly with oil.
Using a fork, combine streusel ingredients until well mixed and crumbly. In a separate bowl, do the same with the crumb topping ingredients. Set both aside.
In a large mixing bowl, combine all dry ingredients except walnuts. Melt the butter in a glass measuring cup, then whisk in the egg. Add milk and vanilla, then pour into mixing bowl and mix until all ingredients are just combined. Fold in nuts.
Divide the batter equally between the two prepared bread pans, then sprinkle half the streusel mixture onto each loaf. Gently drag a knife through the batter, swirling it from side to side to drag some of the streusel crumbs down into the batter to ensure more even distribution of the streusel. If you're wanting the tunnel o'streusel, then skip the swirling.
Bake for 30 minutes in the preheated oven.
When the timer goes off, remove bread from oven and cover each loaf with half of the crumb topping mixture, then quickly place them back in the oven.
Bake for another 30 minutes, or until a toothpick comes out clean.
Allow to cool for 10-15 minutes in pan, then carefully lift the loaves out of the pans using the parchment. Set them on a cooling rack, and let them cool completely before cutting (if you can stand to wait that long).
Slice and enjoy!
Notes
These loaves also freeze beautifully. Simply place a completely cooled loaf in a zip-topped plastic bag, remove as much air as possible, and put in your freezer. Allow to thaw at room temperature before slicing.Quick bread recipe adapted from Better Homes and Gardens' New Baking Book.