Preheat your oven to 350°F (180°C). Butter a 9-inch (23 cm) round cake pan, line with parchement paper, then butter the paper. Set aside.
Make the Cinnamon Filling Cream together the softened butter, brown sugar, flour and cinnamon in a small bowl until evenly combined. Transfer the cinnamon filling to a piping bag fitted with a medium-sized round tip or a zip lock bag snipped in one corner. Set aside.
Make the Cake In a medium bowl, whisk together the flour, sugar, baking powder and salt.
In a large jug, whisk together the milk, eggs, oil and vanilla.
Pour the wet ingredients into the dry ingredients and whisk just until a smooth batter is formed, taking care not to over mix.
Transfer the cake batter into the prepared pan. Starting in the center of the cake, pipe the cinnamon filling in a spiral pattern until you've reached the edge of the tin. (This will bake into the cake and create that classic cinnamon roll spiral pattern.)
Bake for about 1 hour, until a cake tester inserted in the center comes out clean. Let cool in the pan for 10 minutes and then transfer to a wire rack.
Make the GlazePlace the cream cheese in a medium, microwave safe bowl and microwave for 30 seconds, or until melted. Once soft, add the powdered sugar, milk and vanilla and whisk until a smooth glaze is formed.
Pour the glaze over the cake while it is still warm. Let set before serving.
Store in an airtight container in the refrigerator for up to three days.