Position a rack to the center of the oven and preheat to 350°F.
In a heat-proof bowl that fits over the top of a medium pot, add the white chocolate, butter, and molasses. Add three inches of water to the medium pot and place the bowl over the top. Using the double-boil method, bring the pot of water to a simmer and melt the chocolate, butter and molasses together, stirring constantly to combine. When everything is melted, move the bowl to the counter and add the sugar and whisk vigorously. The fat of the butter will start to separate, but that’s normal, don’t stress.
In a separate small bowl, whisk together the egg, yolks, oil, vanilla, the instant coffee mix and 1 1/2 teaspoon of espresso grounds. Pouring very slowly and stirring constantly, gradually drizzle the egg mixture into the wet ingredients. It should sieze up into a glossy batter. Add the flour, baking powder and salt and stir together with a spatula.
Pour the batter into a parchment-lined 8x8 inch pan. Tap the pan to evenly spread out the batter, and top with the remaining espresso grounds. Bake for 20-25 minutes or until a toothpick comes out clean.
*And the most crucial step - It will feel kind of cakey right out of the oven, so cool in the fridge for 45-60 minutes or until the bottom of the tin is cool. A longer chill is always better. This will reward you with the ultimate blondie-fudginess (and yes, you can reheat them!)