Preheat oven to 425 degrees F. Place a 10-inch cast-iron or other oven-safe skillet on center rack of oven. Line a baking sheet with parchment paper or a silicone mat and spread apples across the surface. Top apples with lemon juice, brown sugar, cinnamon, cornstarch, allspice and salt; toss with fingers to combine. Sprinkle with cubes of butter. Place baking sheet on rack just below skillet and bake for 15-20 minutes or until apples are golden brown and bubbling. Remove from oven and cool slightly.

Meanwhile, make the Dutch baby: In a large bowl, using an electric hand mixer, whisk eggs until pale and frothy, about 1 minute. Add milk, flour, nutmeg, cinnamon, vanilla and salt and whisk until smooth, about 1 minute.

Add butter to skillet; swirl to coat. Add batter to skillet and return to center rack in oven (you can bake this simultaneously with the apples). Bake 20 minutes or until deep golden brown. Meanwhile, in a large bowl using electric hand mixer, whisk together heavy cream, vanilla and sugar until soft peaks form, about 2-3 minutes.

Remove pancake from oven. Serve warm in skillet topped with roasted apples and whipped cream on the side.