Preheat the oven to 350 degrees F (175 degrees C). Line 24 muffin cups with paper liners.

Bring stout and butter to a boil in a saucepan over medium-high heat, about 5 minutes. Set aside, stirring occasionally, until butter has melted. Mix in cocoa powder until smooth.

Mix flour, sugar, baking soda, and salt together in a bowl until thoroughly combined.

Mix eggs with sour cream in a large bowl using an electric mixer on low until well combined. Add beer mixture slowly, followed by flour mixture, until batter is smooth.

Divide batter between the prepared muffin cups, filling each about 2/3 full.

Bake in the preheated oven until a toothpick inserted into the center of a cupcake comes out clean, 17 to 19 minutes.

Remove from the oven and let cool completely, about 30 minutes. Leave the oven on.

Meanwhile, lay bacon strips on an aluminum foil-lined baking sheet. Baste with 1 1/2 tablespoons maple syrup, covering both sides.

Bake in the preheated oven for 8 minutes. Turn bacon over, baste with remaining syrup, and bake until browned and crisp, about 8 minutes more, watching to make sure not to burn.

Remove bacon and lay strips on parchment paper so they don't stick to foil upon cooling. Let cool completely, 10 to 15 minutes. Chop into pieces.

Combine butter and powdered sugar in a bowl using an electric mixer until smooth. Beat in cream cheese until smooth. Beat in maple syrup. Frost cooled cupcakes and top with bacon bits.