Preheat oven to 350 °F. Grease or line an 8-inch cake pan with parchment paper.
Bloom saffron: Steep saffron threads in 1 tbsp warm cream for 10 minutes.
Mix dry ingredients: In a bowl, whisk almond flour, baking powder, and salt.
Mix wet ingredients: In another bowl, beat melted butter, erythritol, eggs, vanilla, and almond extract until smooth.
Combine: Stir in the saffron cream, then fold dry ingredients into wet until just combined.
Pour and bake: Transfer batter to the prepared pan and smooth the top. Bake 30–35 minutes, until golden and a toothpick comes out clean.
Cool: Let cake cool 10 minutes in the pan, then transfer to a rack to cool completely.
Serve: Dust with powdered sweetener or top with whipped cream and almonds.