Preheat your oven to 425°F (220°C) to create steam for rising.
Lightly grease the cups of your popover pan with oil or cooking spray.
In a mixing bowl, whisk together the eggs and milk until well combined. Add the flour and whisk until smooth. Gently fold in the pesto and grated parmesan cheese.
Pour the batter into the prepared popover pan, filling each cup about halfway.
Place the pan in the oven and bake for 20-25 minutes until puffed and golden brown.
Remove from the oven, let cool slightly, and serve warm.