Preheat oven to 350Grease an 8x4-inch or 4x10-inch loaf pan. Set aside.
For the streusel: in a small bowl, whisk together the brown sugar, white sugar, flour and cinnamon. Break the butter into 3 or 4 chunks and then, using your finger tips, rub the butter into the dry ingredients until dry and crumbly. Set aside.
In a medium bowl, whisk together the flour, baking soda and salt. Set aside.
Peel and dice apples into a small dice (about 1/4-inch). Measure out the required amount and set aside.
In a large bowl with an electric mixer, or the bowl of a stand mixer with the paddle attachment, beat together the butter, sugar, eggs, lemon juice and vanilla, scraping down the sides of the bowl, if necessary.
With mixer on low, add the flour mixture to the batter and mix until well combined. Using a spatula, gently fold in the diced apples. The batter will be quite thick!
To assemble loaf, spread half of apple batter into the bottom of the greased loaf pan. Sprinkle half of the streusel over batter. Top with remaining batter, then finish with the remaining streusel.Repeat layers with remaining batter and streusel.
Bake at 350F for 55 to 65 minutes or until a tester comes out clean. Remove from oven and allow to cool in the pan for 15-20 minutes, before carefully removing from the pan to cool completely on a cooling rack before slicing and serving.
Be sure to read the “Ingredient and Cook's Notes" (above the recipe card!), where I share more detailedtips, variations and substitution suggestions for this recipe!