Arrange a rack in the middle of the oven and heat to 375 degrees. Grease a 9 inch round baking dish with shortening.
In a small bowl mix together gluten-free flour, baking powder, and salt.
In a medium size bowl, mix together the vegetable oil, eggs, sour cream, sugar, and vanilla extract.
Stir the dry ingredients into the batter until well combined.
Pour the batter into the baking dish.
Mix together the sugar and cinnamon to make the swirl.
Sprinkle the swirl over the top. Use a wooden skewer to swirl the mixture into the batter.
Bake for 25-30 minutes until a toothpick inserted comes out clean.
Place on a wire rack to cool.
Make the glaze by stirring together the melted butter, honey, vanilla, and confectioner’s sugar until smooth. Stir in the milk to thin the glaze for spreading.
Pour the glaze over the top of the cake and allow it to set.
Serve.