Directions

• Preheat the oven to 350 degrees F or 180 degrees C for at least 10 minutes.
• Take dry ingredients (all purpose flour, cocoa powder, baking powder, and baking soda in a bowl. Mix well using a wire whisk. Keep it aside.
• Add milk, condensed milk and vanilla extract to the butter. Whisk well till everything is incorporated well.
• Now sift the half of the flour mixture into the wet mixture. Whisk it till incorporated.
• Now sift the remaining flour mixture. Again mix it. Halfway through, switch to the spatula. And stir till it is just combined, do not overmix.
• Grease a 10×15-inch cake roll pan, and line the base with parchment paper.
• Pour the batter into the prepared pan, and spread out evenly. Tap the pan lightly on the surface a few times to level out the batter. Bake for 10 to 12 minutes.
• Take out the cake, invert the pan onto a clean, slightly damp kitchen cloth, and remove the parchment paper from the bottom. Roll up the cake and hold it in place. 
• Make the whipped cream: Using a hand mixer or a stand mixer fitted with a whisk attachment, whip the heavy cream, sugar, and vanilla extract on medium-high speed until medium to stiff peaks form, about 2-3 minutes. 
• Slowly and gently unroll the cake. Spread whipped cream evenly on top, leaving about a 1/2 inch border around the cake. Re-roll the cake without the tea towel. Cover and refrigerate for at least 1 hour. Dust with icing sugar, slice and serve.