First, grease a 9×13 casserole dish. Then, slice the brioche into thick, 3/4-1 inch slices. If the bread isn't stale, bake the slices directly on an oven rack at 200°F (93°C) for 20-30 minutes until the bread is very dry but not toasted.

Next, heat a large skillet over medium. Add the pecans and toast them, stirring often, until they're golden and smell nutty, about 2-3 minutes. Pour the toasted nuts into a small bowl and set aside. Wipe out the pan.

Melt the butter in the skillet over medium-low heat. Cook the butter, stirring frequently. At first it will simmer and foam up. Keep stirring for about 4-5 minutes until the butter smells caramelized and has brown bits on the bottom.

Once the butter is browned, add the brown sugar, maple syrup, and 1/2 teaspoon of Kosher salt. Bring the mixture to a simmer and cook it until the caramel is thickened and the sugar is dissolved, about 1-2 minutes. Add the pecans and stir for another 1-2 minutes until the pecans are glazed. Spread half of the sticky pecans in the bottom of the prepared casserole dish.

In a large shallow bowl, whisk the eggs, whole milk, vanilla extract, bourbon (if using), cinnamon, cardamom, and the remaining 1/4 teaspoon of salt until smooth.

Soak the bread slices for 10-15 seconds per side until the bread is wet but not falling apart. Arrange the slices of bread in two rows, alternating them back and forth in a shingles pattern. Pour any remaining custard over the bread. Then, spoon the other half of the sticky pecans over the French toast.

Cover the dish with a lid or tinfoil. Refrigerate the casserole for at least 1 hour or overnight.

When you're ready to bake the French toast, preheat the oven to 350°F (177°C). Bake the casserole, uncovered, for 40-45 minutes until the edges are caramelized and the custard is set but just a bit wobbly.

Let the French toast casserole sit at room temperature for 5-10 minutes. Then, slice and serve with butter, maple syrup, powdered sugar, berries, or other toppings you like. Enjoy!