Apple Crumble Coffee Cake
Dark brown sugar will work as well as light brown.
I used a relatively runny, but beautifully tangy, sheep's milk yogurt, but regular plain Greek yogurt will work, as well as sour cream.
You can use Honeycrisp or Granny Smith apples. If you cut your apples too big, your cake will be done but the apples will not be, so take your time and make them small.