1. Preheat your oven to 350 degrees.
2. Prepare your Bundt pan by spraying the inside of the pan with a baking spray containing flour (you can find this spray in the baking aisle at your grocery store). This step is so important if you want your cake to slide out of the pan. Set aside.
3. In a bowl combine the flour, sugar, baking soda and salt. Set aside.
4. In a mixing bowl cream together the butter and peanut butter until fluffy.
5. Add the milk, sour cream, vanilla and eggs, mixing until smooth and creamy.
6. Now add 1/3 of the flour mix and 1/3 of the milk mixture to the peanut butter mixture. Slowly mix.
7. Repeat until all of the ingredients are combined.
8. Add the batter to your prepared Bundt pan.
9. Bake for 1 hour and 10 minutes, or until a toothpick inserted into the centre comes out clean.  The cake should not be jiggly at all.
10. Let your cake rest for at least 10 minutes before turning it out onto a plate. (See Tips Above)

Peanut Butter Drizzle:

1. To make the peanut butter drizzle, microwave 1/2 cup of peanut butter on high for about 20 seconds, or until it is runny. Then using a spoon, drizzle all over the cake.