I usually make this up beforehand, and keep it in the fridge until I'm ready to cook it.
Chop your pecans and spread them out on a sheet pan. Pop this into the oven for about 10 - 15 minutes, shaking and stirring a few times to insure consistent toasting. Remove from the oven and set aside.
In a saucepan, over medium high heat, bring the coffee, pepper, sugar, bourbon, and butter to a rapid boil. Simmer for 10 minutes, whisking frequently.
Being careful not to burn yourself (as the pecans may still be warm), loosely chop them all up. It doesn't have to be fine, but you want to chop them up so that they can be used to encrust the trout (not just be a bunch of pecans on the top of them).
Grease a sheet pan (or a cookie sheet that has a lip) with butter, and lay your trout on it. Pour half of your sauce over the fish. Take your pecans and sprinkle them over the fish, lightly pressing them into the sauce. With a pastry brush, brush additional sauce over the pecans.
Pop your pan in the oven and cook for 15 - 20 minutes. Remove from the oven, and, using a spatula, lay out onto plates.