Preheat the oven to 450° F.To make the jam. Add the strawberries, maple syrup, lemon juice, and vanilla to a medium-size pot set over high heat. Bring the mixture to a boil, once boiling, use a spoon to break down and mash the berries. Continue to cook for 5-8 minutes or until the jam has reduced and thickened by 1/Keep warm. Meanwhile, bake the Dutch baby. Using an electric mixer, whisk together the eggs, milk, flour, salt, vanilla, and 2 tablespoons melted butter until the batter is smooth, about 1 minute. Make sure no large clumps of flour remain.Melt the butter in a 10-12 inch cast iron skillet set over medium heat. Allow the butter to brown until it smells toasted and is a deep golden color, about 3-4 minutes. Pour the batter into the hot skillet. Place the skillet in the center of the oven and bake for 15 minutes or until the pancake is fully puffed and browned on top. DO NOT open the oven during the first 15 minutes of cooking or you might deflate your Dutch baby.As soon as the Dutch baby comes out of the oven, top it with pats of butter, then warm jam. Cover the surface with jam! Add whipped cream if you'd like, Enjoy!