Grease a 8 x 8 pan with the butter.

Preheat the oven to 350 degrees F.

In a large bowl, beat together the sugar, oil, vanilla and egg.

In a medium bowl, sift together the flour, baking powder and salt. Add to the egg mixture.

Add the milk and beat.

Pour the batter into the greased pan.

In a small bowl, mix together the ingredients for the cinnamon swirl.

Spread the cinnamon mixture over the batter.

Cut through the batter with a table knife and swirl.

Bake in the oven for 30 minutes (convection oven) or until a toothpick comes out dry from the cake.

Let the cake rest for 15 minutes, then take out of the pan and serve.