To make almond brittle: Toast almonds at 300˚F until light brown and fragrant, 8 minutes. In medium saucepan, combine sugar, corn syrup, water, and salt, making sure to brush down sides of pan to avoid sugar crystals forming. Bring to boil then reduce heat and cook on medium high without stirring until mixture begins to appear golden amber. (Once you get some color on the sides of pan, swirl sauce to evenly distribute caramel.) When entire mixture is golden amber, turn heat off and immediately add salt and toasted almonds, stirring with spatula to combine. Spread evenly onto greased baking sheet and allow to cool completely. Once cool, break into 15 pieces and set aside.
To make cupcakes: Preheat oven to 350˚F. Line two (2) 12-inch muffin tins with 15 paper liners so there are 7 liners in one tin and 8 liners in other. (Be sure to distribute liners evenly in each tin.)
In a large bowl, sift together flour, sugar, cocoa powder, baking soda, baking powder, and salt. In medium bowl, whisk together buttermilk, oil, vanilla, hot water, and espresso powder. Add egg and whisk thoroughly to combine. Slowly add wet ingredients to dry ingredients and whisk until smooth.
Drop 3 tablespoons batter in each of 15 paper-liners in tins. Bake 18-20 minutes, until wooden toothpick inserted in center of cupcake comes out clean. Allow to cool in pans 20 minutes.
To make glaze: In small saucepan, combine chocolate, butter, and corn syrup. Melt over low heat and whisk to combine. Stir in heavy cream, sugar, vanilla, espresso powder, and salt. Bring mixture to boil over medium heat; cook 5 minutes until thickened then remove from heat. Whisk in cayenne and cinnamon. Cover and let stand 10 minutes to cool.
To serve, remove cupcakes from pan and top each with spoonful of glaze and piece of almond brittle.