• Preheat the oven to 350°F.
• Grease a 10 x 15-inch jelly roll sheet pan with nonstick spray or oil and line with parchment paper.

Make the Cake Batter:

• Mix the flour, cocoa powder, and baking powder in a bowl.
• Beat the eggs in a separate large bowl with an electric hand mixer at medium speed until thick and pale yellow, about 2 minutes.
• Add the sugar and salt and blend on medium speed for 2 minutes.
• Add the oil and milk to the egg mixture and mix on medium speed for 1 minute.
• Gently fold the flour cocoa mixture into the egg mixture and blend it at low speed. Don't overmix - just mix until combined so the cake will come out fluffy.

Bake the Cake:

• Spread the batter evenly into the prepared jelly roll pan and bake in the center of the oven for 10 minutes until cooked.
• Let it cool for about 2 minutes, then loosen the edges of the cake from the pan.
• Lightly dust it with half the sifted cocoa powder and top with a piece of parchment paper and a cutting board. Turn out the cake from the pan onto the parchment/cutting board. Immediately roll the cake loosely on the parchment paper using the long edge.
• Starting with the long edge closest to you, folding over the parchment can help create that first center curl. The parchment paper will prevent the warmed cake from sticking together while cooling in the rolled state. A clean kitchen towel can be used instead. Don't worry about cracks - the ganache will hide them.
• Place the rolled cake on a cooling rack seam side down and cool completely for at least 30 minutes to 1 hour.

Make the Filling:

• Pour the vanilla extract into a small saucepan over low heat and sprinkle the gelatin over.
• Stir with a small fork or whisk until the gelatin is dissolved. Remove from heat and set aside.
• In a large mixing bowl, using a hand mixer fitted with whisk attachment, add the heavy cream, powdered sugar and sifted cocoa powder.
• Beat for 3 or 4 minutes until soft peaks form.
• Using a small spatula, scrape the vanilla gelatin mixture into the chocolate whipped cream and beat on high speed until stiff peaks form, 1 to 2 minutes.
• Cover and refrigerate for 30 minutes while the rolled cake cools.

Fill the Cake:

• Line a cookie sheet or serving platter with parchment paper and set aside.
• Gently unroll the cake on the working surface.
• Starting at the most curved end, add a few tablespoons at a filling time, then gently start the cake roll. Continue adding tablespoons of filling before rolling the remainder section of the cake. Note: You might need to add less filling in the curled center to ensure a tighter cake roll.
• Place the filled rolled cake on the prepared tray seam side down.
• Chill in the refrigerator, seam side down, for 30 minutes up to 1 day before serving.

Glaze the Cake:

• If the cake is refrigerated, remove it and let it sit on a cooling rack or baking rack on parchment paper, and set aside while you make the glaze.
• In a small pot over a low heat, add 1 cup of heavy whipping cream and heat until steaming, 3 or 4 minutes. Don't let it boil.
• Remove from heat and set aside
• In a heat-proof mixing bowl, add the corn syrup and chocolate together. Set aside.
• Pour the heated cream over the bowl of chocolate/corn syrup. Cover the bowl immediately with plastic wrap and set aside undisturbed for 5 to 10 minutes.
• Carefully unwrap your rolled filled cake and place seam side down on a serving platter. Trim each end for an even surface.
• Slowly pour the chocolate glaze over the cake, allowing it to cover the top and sides. Use the back of a teaspoon to spread as desired.
• Allow the glaze to set for 10 to 15 minutes and serve.