Preheat the oven to 175C and line two baking sheets with parchment.

In a bowl, cream the butter, sugar, and oil until light and fluffy. Add the egg and vanilla extract and mix until combined.

Add the flour, baking powder, and spices to the wet mixture and mix until just combined. Chill the dough for 1 hour.

For the streusel, combine the butter, sugar, flour, and spices in a bowl and rub together until you get a breadcrumb consistency.

Remove the cookie dough from the fridge and scoop mounds onto the prepared baking sheets, leaving 2" between each cookie.

Make an indent in each cookie and fill with streusel, using more than you think as the cookies will spread.

Bake for 13-15 minutes until golden brown. Allow to cool on the tray for 5 minutes before transferring to a rack to cool completely.

To make the drizzle, mix the icing sugar and water until you get a drizzling consistency, adjusting if necessary. Drizzle over the cookies and leave to set.