• Preheat the oven to 350°F. Line a 10x15x1 jelly roll pan. Line the pan with parchment paper and lightly spray the prepared pan with nonstick spray. Set it aside.
• Add the flour, cocoa powder, baking powder, and salt to a small mixing bowl. Whisk to combine. Set it aside.
• Using a stand mixer or a medium-sized mixing bowl and a handheld mixer on high speed, beat together the eggs, sugar, oil, and vanilla for 5 to 6 minutes until the mixture is a frothy pale yellow.
• Fold in the flour mixture.
• Evenly pour the cake batter into the prepared pan. Use either a silicone spatula or an offset spatula to spread the batter. Bake for 10 to 12 minutes.
• Remove the cake from the oven, and using a sharp knife, carefully run the tip along the edges of the pan.
• Heavily dust the top of a tea towel with powdered sugar.
• Immediately place the dusted tea towel, powdered sugar side down, on top of the cake.
• Lay a large cutting board on top of the tea towel. The cake pan will be hot, so you will need to be careful to protect your hands. Quickly flip the cake pan over so that the cake is lying on top of the dusted towel.
• Carefully and slowly peel the parchment away from the cake.
• Dust the top of the cake with powdered sugar.
• Flip one end of the tea towel over one of the short ends of the cake. Carefully begin to roll one end towards the other. Once rolled, set it aside to cool completely. While the cake is cooling, make the marshmallow buttercream filling.

Marshmallow Buttercream Filling

• Using a stand mixer or a medium-sized mixing bowl and a handheld mixer on medium-high speed, beat the butter and clear vanilla flavoring for 1 to 1½ minutes, until smooth.
• Add the container of marshmallow fluff and continue beating for 1 more minute until completely incorporated.
• Lower the mixer speed to low and add the powdered sugar ½ cup at a time, alternating with the half and half, until smooth.

Cake Assembly

• Once the cake is completely cooled, carefully and slowly unroll the cake. If there are a few small cracks, it will be ok.
• Using a silicone spatula or an offset spatula, spread the filling over the top of the cake, avoiding the edges.
• Sprinkle the mini marshmallows over the top of the filling.
• Slowly, with gentle even pressure, carefully roll the cake back in a “roll”.
• Tightly roll the plastic wrap to ensure it holds its shape. Chill the cake in the refrigerator for at least 4-6 hours.
• Once properly chilled, drizzle with the chocolate syrup and garnish with the mini marshmallows. Slice ten ½-inch slices.