Can I use pumpkin pie filling instead of pumpkin puree?
Not for this one. Pumpkin pie filling is already sweetened and spiced, and it will throw off the texture and flavor balance. Use plain canned pumpkin puree.
Can I use homemade pumpkin puree?
Yes, but it is often wetter than canned. If it looks loose or watery, drain it in a fine-mesh strainer (or blot with paper towels) until it is thick, like canned pumpkin. Extra moisture can make the cake dense and the streusel sink.
Why did my streusel melt into the cake?
Usually the butter was too warm or the crumbs were too fine. Use cold butter and stop mixing when you have pea-sized and almond-sized pieces. Also make sure your batter is thick enough, which it should be with the measurements below.
Can I make this in a 9x13 pan?
Yes, with two good options. Option 1 (as written): Bake it in a 9x13 for a thinner coffee cake. Start checking around 25 to 30 minutes. Option 2 (closer to the same thickness): Scale the whole recipe up by 1.5x and bake 30 to 40 minutes, checking early and using the doneness cues below.
What can I substitute for sour cream?
Full-fat plain Greek yogurt works great. In a pinch, buttermilk can work, but the batter will be looser and the bake may take a few extra minutes.
How do I know it is done without drying it out?
Look for a set center that springs back lightly. A toothpick in the center should come out with moist crumbs, not wet batter. If you like numbers, an instant-read thermometer in the center should read about 200 to 205°F.
Can I add nuts or chocolate?
Absolutely. Add 1/2 cup chopped pecans or walnuts to the streusel, or fold 1/2 cup mini chocolate chips into the batter. Both are very good decisions.