Cream the butter and sugar in a mixer fitted with the paddle attachment until creamed (light and fluffy), about 2 minutes.
Add the egg whites slowly and mix until fully incorporated into a homogenous mass.
Add the flour on low speed until just incorporated.
Spread about 20g / .71oz of batter onto a full sheet pan–sized nonstick rubber mat using a 10-cm / 4-in square stencil and small offset spatula. Repeat until the nonstick rubber mat is filled with squares (about 12 squares per mat), leaving 2.5cm / 1in between each square. Sprinkle sesame seeds evenly on each square’s surface.
Bake until golden brown, about 6 minutes. Shape around a tube 2.5cm / 1in in diameter while hot. If the tuiles cool off and become too firm to shape around the tube, return the sheet pan with the tuiles to the oven to soften them. Repeat with the remaining batter until the desired number of tuiles is obtained.
Reserve in an airtight container for up to 2 days.