Preheat your oven to 350°F (175°C) to prepare for baking.

In a large mixing bowl, whisk together the plain flour, sugar, ground cinnamon, baking powder, and salt until well blended.

In a separate bowl, whisk together the eggs, milk, vanilla extract, and melted butter until smooth.

Gradually pour the wet mixture into the dry ingredients, folding gently until just combined.

Spoon the batter into the greased donut pan, filling each cavity about two-thirds full.

Bake for 20-25 minutes until golden and a toothpick inserted comes out clean.

Let the donuts cool in the pan for about 5 minutes before transferring them to a wire rack.

Melt butter for brushing and combine sugar with cinnamon for the topping.

Brush each warm donut with melted butter and roll in the cinnamon-sugar mixture.

Optional: Drizzle melted chocolate over the donuts once cooled.

Serve with hot chocolate or coffee and enjoy!