Bake brioche bread cubes at 300°F / 150°C for 12–18 minutes until dry. Cool.
Pat pineapple rings very dry. Cook 2 tbsp butter + 3 tbsp brown sugar until bubbling. Caramelize pineapple rings 2–3 minutes per side. Remove and set aside.
Toast ¼ cup sliced almonds in remaining caramel. Remove and set aside.
Preheat oven to 350°F / 175°C. Butter a deep 9×9 inch baking dish.
Whisk together 4 large eggs, ¾ cup granulated sugar, and ¼ tsp salt. Whisk in 1¼ cups whole milk, 4 tbsp melted butter, 1 tsp vanilla extract, ½ tsp cinnamon, and pinch nutmeg.
Fold in dried brioise bread cubes and crushed pineapple with juice. Rest for 15 minutes.
Spread mixture in prepared baking dish. Top with caramelized pineapple rings.
Bake for 55–70 minutes until firm and golden.
Sprinkle 1 tbsp granulated sugar over pineapple. Broil for 1–3 minutes until bubbling.
Cool for 45–60 minutes before slicing. Top with toasted almonds and serve.
