Add all batter ingredients (2 large eggs; 1 cup milk; 1 cup all-purpose flour; 1/4 cup granulated sugar; 2 tablespoons unsalted butter, melted; 1 tablespoon cinnamon; 1 1/2 teaspoons vanilla extract; pinch of salt, optional) to the blender canister. Blend on high until smooth and combined, about 90 seconds.

Allow the batter to rest in the blender canister for 15–20 minutes while you preheat the oven to 450°F and prepare the pan. (Resting lets the flour absorb liquid and improves texture.)

While the batter rests, spray a mini muffin pan or a popover pan very well with floured or non-stick cooking spray.

After the rest, blend the batter briefly (about 15 seconds) to fluff it.

Divide the batter evenly among the prepared pan cavities, filling each cavity about halfway to two-thirds full.

Bake at 450°F for 10 minutes. Do not open the oven door during this time.

Using the oven controls (without opening the oven door), reduce the temperature to 350°F and continue baking for about 4 minutes, or until the popovers are domed, puffed, and golden brown. Watch through the oven window near the end so they don’t burn.

While the popovers are baking, make the topping: melt 1/4 cup unsalted butter in a small microwave-safe bowl (about 45 seconds on high). In a separate small bowl, combine 1/4 cup granulated sugar and 1 1/2 teaspoons cinnamon, stirring to mix.

When the popovers come out of the oven, keep them in the pan and brush them evenly and generously with the melted 1/4 cup butter. Then sprinkle the cinnamon-sugar mixture evenly and generously over the tops with a small spoon.

Remove the popovers from the pan (use a butter knife to dislodge if necessary) and serve immediately. Store airtight at room temperature for up to 4 days; reheat about 10 seconds in the microwave if desired.