Preheat the oven to 350F. Grease a 9” round (or 8” or 9” square) baking pan with cooking spray, line with parchment paper, and place onto a baking sheet.
In a medium bowl, mix together the almond flour, sugar, softened butter, egg, both extracts, and salt until well combined. Set aside.
In a large bowl or measuring cup, whisk together the milk, heavy cream, eggs, sugar, melted butter, vanilla, and salt until well combined. Set aside.
Place 1/3 of the croissant cubes into the bottom of the prepared pan and press down.
Spread ~1/3 of the almond frangipane on top. Spread 1/2 of the raspberry preserves on top, then dollop 1/2 of the fresh raspberries all over. Repeat this process 1 more time.
Press the last 1/3 of croissant cubes on top and spread the last of the almond frangipane on top of the croissants.
Pour the custard all over and gently press down. Top with turbinado sugar and slivered almonds. Let rest for at least 15 minutes.
Bake at 350F for 40-45 minutes, until the top is golden and set, but still slightly wobbly. Optionally broil the top for 1-2 minutes for a toasted effect. Remove from the oven and let rest for at least 10 minutes.
Slice and serve warm with a scoop of vanilla ice cream if desired.