Preparation

• Position a rack in the center of the oven and heat the oven to 400°F.
• In a medium bowl, toss the pear slices with the lemon juice and set aside.

• In a large bowl, beat the eggs with an electric hand mixer on high speed until thick and frothy, about 3 minutes. Add the milk, granulated sugar, vanilla, salt, and lemon zest and mix on low speed until combined. Sift in the flour and mix on low speed until combined (don’t worry if there are lumps).
• Heat a 12-inch cast-iron skillet over medium heat until hot, about 2 minutes. Add the butter, and when it begins to foam, add the pear slices, quickly turning them to coat with the butter, and arranging them in a single layer. Pour the batter evenly over the pears  and transfer the skillet to the oven. Bake until the pancake is set in the middle, the sides have risen, and the bottom is nicely browned, about 20 minutes.
• Sprinkle the pancake with the confectioners’ sugar. Serve immediately with a dollop of crème fraîche, if using.