Make Pecan Pie Filling. Combine pecans, corn syrup, brown sugar, butter, eggs and salt in a medium saucepan over low heat. Stir constantly over low heat until sugars are dissolved.
Cook. Gradually increase the heat and bring the mixture to a slight boil. Once boiling, reduce to a simmer and cook until the mixture thickens (8-9 minutes), stirring constantly.
Add extracts. Remove from heat and stir in the vanilla and maple extracts.
Cool. Cool mixture in the refrigerator for a minimum of 30 minutes.
Make Almond Cream. Combine butter and sugar on medium speed until fluffy in a stand mixer. Scrape down the bowl. Add in both eggs and beat until fully incorporated. Scrape down the bowl again.
Add extracts. Add in the vanilla, almond, and maple extracts. Mix on low until combined. Add almond flour and salt and mix until just combined. Scrape down the bowl and add in all-purpose flour. Stir until combined.
Prep for baking. Preheat oven to 350 degrees and adjust an oven rack to be in the center of the oven. Line two baking sheets with parchment paper and set aside.
Cut croissants. Cut croissants in half horizontally and arrange 4, cut side up, on each baking sheet.
Add almond cream. Spread 2 tablespoons of almond cream evenly on the bottom side of each croissant. Pay close attention and fill to the ends of the croissant.
Add pecan pie filling. Spread 2 tablespoons of pecan pie filling evenly on top of almond cream.
Top croissants. Place the tops back on the croissants, gently press down, and spread an additional tablespoon of almond cream across the top of the croissant.
Bake. Bake one tray at a time for 13-15 minutes or until the almond cream is fully cooked and light brown.
Cool and dust. Allow croissants to cool on their tray. When cool, dust with powdered sugar.