Step 1

Preheat the oven to 350°F. Line to large rimmed baking sheets with parchment paper.

Step 2

In a medium bowl, combine the crumb topping ingredients with a spoon or spatula until combined and crumbly.

Step 3

To the bowl of a stand mixer, or electric hand mixer, add the butter and mix on medium-high speed until light and fluffy, 2-3 minutes. Add the oil and mix for another 1-2 minutes.

Step 4

Add the sour cream, egg, granulated sugar, and vanilla extract and mix on medium-low speed until combined.

Step 5

In a separate medium bowl, whisk together the baking powder, cinnamon, salt, and 1/4 cup of flour. With the mixer running on low speed, add half the dry ingredients, mix, then add the remaining mixture until combined.

Step 6

Use 1/4 cup (or a very large cookie scoop) to scoop out the dough and place them 3 inches apart on the prepared baking sheets. Use the back of a Tablespoon to create a well in to center of the cookie dough. These cookies don’t spread much so shape them the best you can.

Step 7

Fill each well generously with the prepared crumb topping, until it's overflowing slightly.

Step 8

Bake in the preheated oven for 10-12 minutes. Do not over bake—they shouldn’t turn golden brown. They should be slightly underbaked to stay soft.

Step 9

While they’re baking, whisk together the powdered sugar and heavy cream until smooth. Do not add more heavy cream or it won’t set.

Step 10

When the cookies are done, remove them from the oven and drizzle them with the icing. Allow them to cool on the baking sheet for 2-3 minutes then transfer to a wire rack to cool completely.