I've made popovers the same way for a few years now with pretty good success. But this morning it did something different. Preheat the oven and pans to 450. 2 eggs 1 cup flour 1 cup milk 1/4 teaspoon salt 1 tablespoon melted butter. Mix all together, oil the hot popover pan, pour in the batter filling each cup no more than 3/4 full, and into the oven for 20 minutes. Reduce temp down to 350 for another 10 15 minutes. Some consider that overfilling, but it has worked well in the past with the pans I use. Today, all seemed normal, but I had some leftover batter. That was a bit odd. But when I removed the popovers I found out why. The batter and flashed into steam and set, creating an air pocket in the bottom of the pan. I've had small versions of that in the past, but today, each popover did it significantly. Even though there was less batter per popover, they cooked up a bit doughy because there was so much less contact with the pan to transfer the heat. My thoughts are two. One, an over heated pan. But I've not noticed my oven baking off temp and the look, feel and smoke (I'm using cast iron muffin pan and they smoke at that temp) were all as normal. I might have overbeat the batter. Now, I've been using a food processor to mix this batter though I don't remember where I got that tip. 30 seconds in the FP gives it enough work to hold the rising steam and really pop. I used my immersion blender this time. What are your thoughts on these popovers. This is the pan for reference. Works great, releases easily, pops really well with the heat it holds.