Preheat the oven to 180 deg C. Slice your apples into thin slices. Toss them with cinnamon powder and lemon juice, set aside.
In a mixing bowl combine softened butter, brown sugar and cinnamon powder in a small bowl and mix until smooth. You can make this ahead of time and keep it covered in the refrigerator, but bring it back to room temperature before serving so that it is easy to spread.
In a large mixing bowl whisk together the eggs, milk, heavy cream, sugar, freshly grated nutmeg, vanilla extract, almond extract and a pinch of salt until smooth. I like making the custard in a shallow dish rather than a deep bowl because it makes dipping the bread much easier.
Using a sharp knife, make a cavity/pocket in each brioche bread slice, spoon the cinnamon butter into the middle and stuff it with the sliced apples. Dip each slice of bread into the custard, making sure both sides are coated.
Arrange the slices cut side up in a 9 inch casserole dish. Stuff the leftover apple slices around the dish and dollop the remaining cinnamon in the crevices, pour over the extra custard and let the bread soak it up for 15 minutes.
Top with flaked almonds and granulated sugar. Bake for 25-30 minutes or until the top is golden and toasty, it has risen and the center is still wobbly.
Serve it warm with maple syrup, whipped cream.