Preheat oven to 425. Add room temperature eggs and room temperature milk into a blender and process until smooth. If you don’t have time to let the eggs and milk come to room temperature, let the eggs sit in warm water for a couple minutes and microwave the milk for 10 seconds.
Add in the packed flour, salt, and vanilla. Puree until smooth. Set aside.
Heat cast iron skillet over high heat. Once hot, add the butter and swirl to coat. Carefully pour the blended batter into the middle of the skillet and immediately remove from heat and transfer into the oven.
Bake 20-25 minutes. Serve immediately with melted butter, powdered sugar, and fresh lemon juice.