Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Cream together the softened butter, vegetable oil, and brown sugar until light and fluffy. Add the egg and vanilla extract, and mix until combined.

In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon. Gradually add this to the wet mixture, mixing just until combined.

For the streusel, combine the softened butter, brown sugar, flour, cinnamon, and salt until it resembles coarse crumbs.

Scoop dough onto the lined baking sheet, indenting the center of each scoop. Fill with the streusel mixture.

Bake for 10-12 minutes until golden around the edges.

While cooling, mix the icing ingredients until smooth and drizzle over the cookies.