Several reasons can lead to dense popovers. Ensure your ingredients are room temperature, your batter is rested for at least 15 minutes, and your ingredients are fully incorporated. When mixing the flour into the batter, do not overmix. This causes the gluten to activate, leading to heavy, chewy popovers. Lastly, resist the urge to open the oven door while baking, as this can cause the popovers to deflate, leading to chewy interiors.