Preheat your oven to 425°F (220°C). Place the empty popover pan inside while heating. A hot pan helps the popovers rise quickly and evenly. This step is very important for a good puff.

In a bowl, mix flour and salt. In another bowl, whisk eggs and milk until smooth. Slowly add the wet mixture to the dry ingredients. Mix until smooth and lump-free.

Pour melted butter into the batter. Mix gently until combined. The batter should be thin, almost like pancake batter. Do not overmix or the texture may change.

Carefully remove the hot pan from the oven. Grease each cup with butter. Make sure every corner is coated. This prevents sticking and helps create a crisp outer layer.

Pour the batter into each cup. Fill only halfway. This gives space for the popovers to rise tall. Work quickly so the pan stays hot.

Place the pan back into the oven. Bake at 425°F for 20 minutes. Do not open the oven door during this time. Steam inside helps them rise.

Reduce the oven temperature to 350°F (175°C). Continue baking for another 10 minutes. This step helps the inside cook fully without burning the outside.

Take the popovers out of the oven. Pierce each one with a small knife. This releases steam and keeps them crisp. Serve warm with butter or jam.