1 large sweet potato, peeled and cut into 1/2-inch dice
1 apple, diced
1/4 cup chopped hazelnuts, walnuts or pecans
2 Tbsp brown sugar
1 Tbsp cinnamon
1/4 tsp ground nutmeg
Zest of one lemon
1 package Pepperidge Farm puff pastry (2 sheets), thawed
1 egg beaten with 1 tsp of water
Preheat oven to 400°F. Set out two 12-muffin tins.
Place sweet potato cubes in a small sauce pan, covered by a few inches of cold water. Bring to the boil, then reduce heat to medium and cook for 8-10 minutes, until potato is quite soft.
While the potato is cooking, combine apple, nuts, sugar, cinnamon, nutmeg and lemon zest in a mixing bowl. Drain the cooked potato and add while hot to the bowl, stirring to combine. The heat of the potatoes will begin to soften the sugar, which is exactly what you want to happen. Let the mixture cool to room temperature while you prepare the pastry cups.
Roll out each sheet of puff pastry, and trim 1/2 inch off the edges all the way around. With a sharp knife, cut each sheet into 4 squares. Fit 4 pastry squares into each muffin tin, being sure to space them out so each has room to expand. Divide sweet potato mixture among the 8 muffin cups.
Using a paint brush, paint the pastry with the beaten egg. Place in the upper third of the oven and bake for 20 minutes. Remove from the oven and let cool for 10 minutes, until the pastry releases easily from the muffin tin. Serve warm.