• Make the brown butter: Place a stainless steel saucepan over medium heat. Add the diced butter and stir to melt completely. Bring to a simmer and cool without stirring for 2 minutes. The butter will bubble up as water evaporates from it. Start stirring the butter again to watch it change color. If needed, lift the pan off the heat so the butter bubbles down, allowing you to see what color it is. Take the butter off the heat when the milk solids (the solids that deposits in the bottom of the pan) are golden and the butter gives off an enticing nutty aroma. Swirl the pan for a few seconds to make sure the butter is ready, then pour it butter into a mixing bowl or measuring cup and set aside to cool for 10 minutes.
• For the black sesame and chocolate financier cake: In the bowl of a food processor (or a mini food processor, or the food processor attachment of a hand blender), combine the toasted black sesame seeds, flour, brown sugar, and salt. Process for about 2 minutes, or until the mixture turns gray (scrape down the bowl as needed.)
• Transfer the dry ingredients to a large mixing bowl. Add the powdered sugar and almond flour, then whisk to thoroughly combine. Add the egg whites and whisk until fully incorporated. Add the brown butter, canola oil, sesame oil, and black gel food coloring, if using, and whisk until fully incorporated. Cover the bowl with plastic wrap and refrigerate the butter for at least 1 hour, or up to 3 days.
• To bake the black sesame and chocolate financier cake: Preheat the oven to 350°F (175°C). Generously butter a 9-in (23-cm) savarin or ring mold pan, lightly dust with flour, then tap out the excess. Spoon the financier batter around the mold (the batter will be a bit stiff because it was refrigerated.) Once you’ve spooned all the batter into the mold, use the back of the spoon to evenly distribute it around the mold and level out the top.
• Bake for 35 to 40 minutes, or until the financier cake is puffed up, light golden around the edges, and fully set (a toothpick inserted in the center of the cake should come out clean.) Transfer the pan to a rack and let cool for 10 minutes, then invert the cake onto the rack to cool completely. Do not let the cake fully cool into the pan because it could get stuck to it for good (especially if you’re using an aluminum pan.)
• For the chocolate ganache: In a double-boiler, add the chocolate and stir until fully melted. (You can also melt the chocolate in a measuring cup in the microwave by heating it at a low power level for 10 seconds at a time. Stir thoroughly before returning to the microwave and repeat until the chocolate is fully melted.) Add the butter and oil and whisk until the butter is melted and the oil is incorporated. If you melted the chocolate in a double-boiler, transfer the warm ganache into a measuring cup.
• Place the rack with the cooled financier cake over a parchment paper-lined baking sheet. (Lining the baking sheet with parchment paper will make it easy to recover and save the excess ganache for another use.) Slowly pour the ganache around the financier cake, making sure the cake is fully covered. Sprinkle the ganache with sesame seeds and flaky sea salt. Let the ganache set fully, then transfer the cake on a serving plate or the base of a cake dome. Cover and keep at room temperature for up to 3 days.
• SERVING: Distribute candied lemon zest around the top of the cake, if desired. Slice and serve.
• STORAGE: Store leftover cake under a cake dome or in an airtight container at room temperature for up to 3 days.

NOTES

• How to toast sesame seeds: Preheat the oven to 300°F (150°C). Spread the sesame seeds over a baking sheet and bake for 10 minutes, shaking the pan once or twice during the process. Let cool completely. Store in an airtight container until needed.
• How to bake individually-sized black sesame and chocolate financiers: Line the cups of two 12-cup muffin pans with parchment paper cups. Fill each cup with about 2 tbsp (30 ml) of financier batter. Bake the financiers at 350°F (175°C) for about 15 minutes, or until puffed up, lightly golden around the edges, and fully set (a toothpick inserted in the center of one of the financiers should come out clean.) Prepare the ganache as directed, then dip the tops of each financier into the warm, liquid ganache. Sprinkle with sesame seeds and flaky sea salt. Let the ganache set fully, then store in an airtight container at room temperature for up to 3 days. Right before serving, garnish with candied lemon zest, if desired.
• Recipe Credit: Recipe from Chef Patrice Demers adapted for the home kitchen by Marie Asselin, FoodNouveau.com.