Preheat your oven to 350°F (175°C). In a buttered baking dish, arrange the sliced pears in an even layer.
Mix the Custard
In a mixing bowl, whisk together the almond flour, heavy cream, whole milk, granulated sugar, eggs, vanilla extract, almond extract, and salt until smooth and well combined.
Pour Custard Over Pears
Pour the almond custard mixture evenly over the arranged pears, ensuring they are well covered.
Prepare the Topping
In a small bowl, combine the sliced almonds, melted butter, and brown sugar. Mix until the almonds are coated.
Add Topping
Sprinkle the almond topping evenly over the custard and pears in the baking dish.
Bake the Gratin
Bake in the preheated oven for 35-40 minutes, or until the custard is set and the almonds are golden brown.
Cool and Serve
Allow the gratin to cool slightly before serving. It can be enjoyed warm or at room temperature.