Preheat oven to 350°F (175°C). Grease an 8×8-inch metal baking dish.

In a large bowl, whisk flour, 6 tablespoons sugar, cinnamon, and salt.

In another bowl, whisk melted butter, eggs, and milk until smooth.

Pour wet ingredients into dry ingredients and stir gently until just combined.

Spread batter evenly into prepared baking dish.

Sprinkle remaining sugar (and coarse sugar if using) over the top.

Bake for 40–45 minutes, until golden and center is just set.

Cool 15 minutes before slicing. Serve warm.