Preheat your oven to 425°F. Line two half-sized sheet pans with parchment and brush with melted butter.
In the bowl of a stand mixer fitted with a whisk, whip the egg whites to soft peaks, add the sugar, and continue to whip to stiff peaks. Scrape the meringue into a bowl.
In a separate mixing bowl with paddle attachment, beat the almonds, powdered sugar and eggs on medium until they’re light and increased in volume, about 3 minutes. Turn the mixer down to low and add the flour, stirring just until it disappears.
Remove the bowl from the mixer and gently fold in the meringue. Lastly, fold in the melted butter.
Divide the batter evenly between the two pans, spreading it as evenly as possible over the two pans. Bake for 5-7 minutes, until the layers are lightly browned. Remove from the oven and place the pans on the stove top.
Run a knife along the edge of baking sheet to loosen and invert cake onto prepared towel. Peel away parchment and roll cake into a log inside towel. Transfer, seam side down, to a wire rack and let sit until just barely warm, about 20 minutes.