Preheat the oven to 350°F. Spray the baking pan with cooking spray.
In a large bowl, combine the oil, sour cream, milk, eggs, sugar, and vanilla with a whisk until the wet ingredients are smooth.
In a medium bowl, toss the flour with the salt, baking powder, and chocolate chips.
Add the dry ingredients to the wet and mix the batter together with a wooden spoon or spatula until just combined and no flour streaks remain.
In the medium bowl that you used for the dry ingredients, combine the streusel ingredients well (using your fingers is best!) until you have a mixture of fine and coarse crumbs.
Add half of the coffee cake batter to the pan and spread it to the edges. Sprinkle it with half of the streusel mixture. Repeat these layers, finishing with an even layer of the streusel.
Bake for 40-45 minutes, until a toothpick inserted in the center of the coffee cake comes out clean.
Allow the coffee cake to cool for at least 30 minutes, it will slice even better when completely cooled. Slice into 12 even pieces and serve.
Nutrition facts are sometimes provided below and are calculated using an online calculator. With specific brands of ingredients and additions, omissions, or substitutions the nutrition facts may change. We encourage you to use your own nutrition facts calculator to obtain the most accurate nutrition facts for your meal.