Preheat the oven to 350 degrees F. Line a 12-cup muffin pan with paper liners; set aside. Whisk the flour, salt and baking soda in a medium bowl. Whisk the cocoa powder and espresso powder in a large bowl. Heat the milk in a small saucepan over medium heat until hot but not simmering; whisk into the cocoa mixture until smooth. Whisk in the granulated sugar until dissolved, then the vegetable oil, eggs and vanilla. Whisk in the flour mixture until just combined.
Divide the batter among the prepared muffin cups, filling each about two-thirds full. Bake until a toothpick inserted into the centers comes out clean, about 20 minutes. Let cool 5 minutes in the pan, then remove to a rack to cool completely.
Meanwhile, make the frosting: Put 4 ounces bittersweet chocolate in a microwave-safe bowl and microwave in 1-minute intervals, stirring occasionally, until smooth. Let cool to room temperature. Beat the butter and salt in a large bowl with a mixer on medium-high speed until fluffy, about 2 minutes. Reduce the mixer speed to low and gradually beat in the confectioners' sugar. Increase the speed to medium high and beat until fluffy again, 2 to 3 minutes. Beat in the cocoa powder, milk and vanilla until smooth. Beat in the melted chocolate until very fluffy and smooth, 2 to 3 minutes.
Frost the cupcakes, using an offset spatula to mound the frosting into smooth rounded domes. Refrigerate until the frosting is firm, about 30 minutes.
Meanwhile, combine the white chocolate and 1 1/2 tablespoons coconut oil in a medium microwave-safe bowl. Combine the remaining 2 ounces bittersweet chocolate and 1/2 tablespoon coconut oil in a small microwave-safe bowl. Microwave each chocolate separately in 30-second intervals, stirring occasionally, until melted and smooth. Stir the orange gel food coloring into the white chocolate, then transfer to a shallow bowl or liquid measuring cup; let cool slightly. Let the bittersweet chocolate mixture cool until it's thick enough to pipe, then transfer to a resealable plastic bag and snip a small corner.
One at a time, turn each cupcake upside down and dip the top in the orange chocolate mixture; rotate to coat and let the excess drip off. Turn right-side up and pipe lines of bittersweet chocolate to look like the seams of a basketball. Let set at room temperature, about 30 minutes.