Step 1

Grease 2 bundt cake pans (5.5 inches diameter) with butter. You can also use a 7.5 to 8 inches round pan.

Step 2

In a bowl take 1 tablespoon unsalted butter.

Step 3

On a low heat begin to melt butter. You only need to melt the butter.

Step 4

Remove the bowl from the stove burner and keep on the countertop as soon as the butter is melted.

Step 5

Add ¼ cup finely chopped nuts. You can use any crunchy nuts. I have added an equal mix of chopped pistachios, cashews and almonds.

Step 6

Then add 4 tablespoons brown sugar, 1 tablespoon whole wheat flour and 1 teaspoon cinnamon powder.

Step 7

Mix very well. Keep the streusel filling aside.

Step 8

In a mixing bowl or a stand mixer bowl take sugar and softened unsalted butter. Meanwhile preheat oven at 180 degrees Celsius/356 degrees Fahrenehit for 20 minutes.

Step 9

Using the paddle attachment of a stand mixer, beat on medium to high speed till the butter becomes fluffy. Scrape the sides while beating.

Step 10

Then add baking powder, baking soda, vanilla extract and apple cider vinegar or lemon juice. You can even add ½ teaspoon vanilla essence or 1 tablespoon white vinegar.

Step 11

Beat on medium speed for 30 seconds.

Step 12

Add sour cream. Instead of sour cream you can also use fresh curd or yogurt. Do make sure that the yogurt is thick and not thin or watery.

Step 13

Beat on medium low speed for 30 to 45 seconds.

Step 14

Add whole wheat flour and 1 to 1.25 cups water or add as required.

Step 15

Beat on low speed for a minute or more till everything is mixed well. If there are many lumps then beat for some more seconds. Do not over beat. If batter looks very thick then add more water. I added 1.25 cups water. The batter consistency is thick. Some tiny lumps are fine in the batter.

Step 16

Take spoonfuls of the batter and place it in the greased bundt pan. Fill till ⅓ of the volume of the bundt pan. Using a spatula even the batter.

Step 17

Now take spoonfuls of the prepared streusel stuffing and top it all over evenly on the cake batter.

Step 18

Again add some batter and fill it till ⅔ or ¾ ᵗʰ volume of the pan.

Step 19

With a spatula make the batter even from top.

Step 20

Place the cake pans in the preheated oven in the center rack. If using an OTG, then use the bake option where only the bottom heating element is heated.

Step 21

Bake the cake at 180 degrees Celsius/356 degrees Fahrenheit for 45 to 50 minutes or till the top is golden. since temperatures in ovens vary, do keep a check.

Step 22

To check doneness, insert a bamboo skewer in the cake and it should come clean. If there is sticky batter on the skewer, this means the cake needs to be baked for some more time. For cooling keep the cake on a wired rack.

Step 23

When cooled completely, unmould the cake from the pan.

Step 24

Slice and serve streusel sour cream coffee cake with coffee or tea or as a dessert.