Start by placing the cornflakes in a sturdy zip-top bag or food processor. Crush them into fine pieces, which should take about 2-3 minutes.

Combine the crushed cornflakes with sugar and cinnamon in a mixing bowl to create the coating.

In a medium skillet, melt butter over medium heat until it sizzles, about 1-2 minutes. Add the cornflake mixture to the skillet and toast for 3-4 minutes until golden and fragrant.

In a shallow dish, whisk together the eggs, milk, and vanilla extract until frothy, about 1-2 minutes.

Thickly slice the French bread, aiming for at least 1-inch pieces. Dip each slice into the egg mixture for 1-2 minutes per side.

Once soaked, press each slice of bread into the toasted cornflake mixture, ensuring even coating.

In a skillet, heat vegetable oil and an additional tablespoon of butter over medium heat until shimmering. Place the cornflake-coated bread slices in the skillet, cooking for about 3-4 minutes per side until golden brown.

Transfer the Cinnamon Cornflake French Toast to a paper towel-lined plate to drain excess oil. Serve immediately while hot and crispy.