Measure out all ingredients and set out milk, sour cream, egg, and leftover cranberry sauce to room temperature.
Preheat the oven to 350°F.
Line an 8x8 metal baking pan with parchment paper.
First make the streusel. In a medium-small bowl, stir together flour, brown sugar, granulated sugar, cinnamon, and salt. Drizzle melted and cooled (but still warm) butter over the mixture and use a fork to gently toss the ingredients together until combined, no longer dry, but still clumpy. Don’t over-mix or the streusel will turn into a paste (a tasty paste but still a paste not a crumble, lol) Set aside.
In a medium bowl, add flour, sugar, baking powder, cinnamon, and salt. Whisk well with a metal whisk (or fork) to combine. Set aside.
In a large mixing bowl, combine eggs, oil, sour cream, milk and vanilla. Mix well using a metal whisk or electric beater.
Add dry ingredients to the wet ingredients and mix until combined.
Spread the batter into parchment lined baking pan. Dollop with spaced spoonfuls of cranberry sauce then spread into one even layer. It's okay if a little mixes with the batter.
Sprinkle streusel mixture over the top.
Bake for 30–33 minutes. Slice and enjoy slightly warm or cooled!
Notes
See post for process photos as well as an easy cranberry sauce recipe if needed.Nutrition Facts below are estimated per square (1 of 9) of coffee cake using an online recipe nutrition calculator. Adjust as needed if sliced smaller and enjoy!