Preheat oven to 350°F (175°C) and line a 12-cup muffin tin with paper cupcake liners.
In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt until combined.
Add brown sugar and granulated sugar to the dry ingredients and mix well.
Stir in canola oil, buttermilk, egg, and vanilla extract just until combined, avoiding overmixing.
Divide the batter evenly into cupcake liners, filling each about three-quarters full.
Sprinkle graham cracker crumbs over the batter in each cup.
Bake for 21 to 23 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Allow cupcakes to cool completely in the tin.
Fill a medium saucepan with about 1 inch of water and bring to a gentle simmer.
In a large, clean mixing bowl, whisk together egg whites, granulated sugar, cream of tartar, and salt.
Place the bowl over the simmering water without the bottom touching the water and whisk constantly until the mixture reaches 120°F (49°C) and sugar dissolves.
Remove the bowl from heat, add vanilla extract, then beat with an electric mixer on high speed until glossy, stiff peaks form.
Spread or pipe the meringue frosting over the cooled cupcakes using a star tip for decoration.
Lightly toast the meringue with a kitchen torch or place under the oven broiler on the lowest rack for about 2 minutes until golden brown, watching closely.
Top each cupcake with a piece of graham cracker and a segment of milk chocolate. Serve immediately or store in a cool place.