Preheat your oven to 325°F. Spray the bottom and sides of a 9x5x3-inch loaf pan with cooking spray; line with a parchment paper sling. Set aside.

Dissolve coffee granules in 1 teaspoon boiling water; set aside.

In a large bowl, whisk together all-purpose flour, cocoa powder, baking powder, and salt until well-combined.

In the bowl of a stand mixer with the paddle attachment, beat butter and sugar on medium-low speed until light, fluffy, and smooth, about 2 to 3 minutes.

Beat in eggs, one at a time, scraping down the sides of the bowl after each addition. Beat in sour cream, vanilla extract, and coffee until just combined.

Gradually stir flour mixture into butter mixture just until a batter forms and no dry spots remain. Pour and spread batter evenly into prepared loaf pan.

Bake for 55 minutes to 1 hour, or until a toothpick inserted in the center comes out clean.

Cool loaf in pan for 10 minutes, then use parchment to transfer loaf to a cooling rack. Cool completely.

Once loaf is fully cooled, place semisweet chocolate in a medium bowl.

In a microwave-safe measuring cup, heat heavy cream for 30 seconds on High until very hot but not boiling. Pour over chocolate; add oil. Let sit for 5 minutes, then stir until smooth.

Spoon and spread topping over top of loaf, letting it drip down the sides. Transfer loaf to refrigerator; chill for 30 minutes to set the topping.

Slice and serve loaf as desired. Store leftovers tightly covered at room temperature for up to 2 days; do not refrigerate.