Begin by pouring whole milk into a large, heavy-bottomed saucepan. Set the heat to medium and gently warm the milk, stirring continuously until it reaches 195°F.

In a mixing bowl, whisk together all-purpose flour, granulated sugar, and kosher salt until combined, then set aside.

In a small saucepan, melt salted butter over low heat until fully melted.

Add the flour mixture to the melted butter once the milk reaches temperature, stirring to form a smooth paste.

Gradually whisk the flour and butter mixture into the heated milk, ensuring there are no clumps.

Increase heat to medium-high and stir until the mixture starts to boil. Reduce heat to low and simmer for about 5 minutes, continuing to stir gently.

Remove from heat, cool slightly, ladle into bowls, drizzle with butter, and sprinkle cinnamon-sugar on top.