Step 1: Preheat your oven to 400°F (200°C) and line two baking sheets with parchment paper.
Step 2: Roll out the puff pastry and use a 4-inch round cutter to cut out 12 circles. Place them on the baking sheets.
Step 3: Score a smaller circle inside each pastry round, about 1/2 inch from the edge, and prick the center with a fork.
Step 4: In a large skillet, melt the butter over medium heat. Add the diced apples, brown sugar, cinnamon, and nutmeg.
Step 5: Sauté the apples for 5-7 minutes until they are tender but still hold their shape. Remove from heat and let cool slightly.
Step 6: Spoon about 2 tablespoons of the apple mixture into the center of each pastry round.
Step 7: Brush the edges of the pastry with a beaten egg wash.
Step 8: Bake for 15-18 minutes or until the pastry edges are golden brown and puffed. Remove from the oven and let cool completely.
Step 9: In a small saucepan, combine the granulated sugar, corn syrup, and water. Bring to a boil over medium-high heat.
Step 10: Using a candy thermometer, cook the syrup until it reaches the soft-crack stage (270-290°F).
Step 11: Remove the syrup from the heat and immediately stir in the red gel food coloring until the desired ‘poison’ red is achieved.
Step 12: Carefully drizzle or spoon the red glaze over the apple filling on each tart, allowing some to drip over the edges.
Step 13: Let the glaze set for at least 10 minutes before serving your poison apple tarts recipe.