Preheat the oven to 350°F (175°C). Line a baking dish or sheet with parchment paper.

In a mixing bowl, whisk together the flour, granulated sugar, baking powder, and salt.

In a separate bowl, combine the milk, vegetable oil, and egg. Mix well.

Gradually add the wet ingredients to the dry ingredients and mix until a dough forms.

Lightly flour your countertop and roll the dough into a rectangle, about ½ inch thick.

Brush the melted butter over the rolled dough.

In a small bowl, mix together brown sugar and ground cinnamon. Sprinkle this mixture evenly over the buttered dough.

Starting from one edge, tightly roll the dough into a log.

Cut the log into 12 equal pieces and place them in the prepared baking dish.

Bake in the preheated oven for 25 minutes, or until the rolls are golden brown.

While the rolls are baking, prepare the icing by mixing powdered sugar, milk, and vanilla extract in a microwave-safe bowl.

Once the rolls are done baking, drizzle the icing over them while warm.