Preheat the oven to 350 degrees F. Lightly spray two 12-cup financier pans or mini muffin pans with nonstick spray.
Heat the butter in a small saucepan over low heat, stirring constantly, until browned and fragrant, 7 to 10 minutes. Remove from the heat and pour over the peanut butter in a medium heatproof bowl and stir to combine. Set aside.
Stir together the sugar, flour, almond flour and salt in a large bowl. Add the egg whites and stir until well combined. Add a third of the almond flour mixture to the peanut butter mixture and stir to combine then add back to the almond flour mixture. Mix well until thoroughly combined. Spoon the batter into a piping bag and pipe into the prepared pans, dividing the batter evenly among the molds and filling them almost to the top.
Bake until the financiers are golden brown and spring back to the touch, 18 to 20 minutes. Remove from the oven and let cool completely.
Remove the financiers from their molds, top each with 1/2 teaspoon of the jam and a slice of strawberry. Sift confectioners' sugar over the tops and serve.