Crafting a great single origin espresso should be approached the same was as you would in creating any other delicious espresso. Separate roasts. Separate profiles. Separate flavors. And then a wonderful espresso.
Espresso is not a tiny cup of coffee. It should not feel like a “tiny cup of coffee”when you drink it. Espresso has a density, intensity, and viscosity (mouthfeel). Whether it's floral and light stone fruit or dense chocolate and dark berry, espresso should still have a definite mouthfeel and density. Properly roasted and executed espresso has a density that supports and balances the clarity. Creating density enhances the clarity, it does not take away from it. Espresso that is thin and bright without the proper amount of sweetness and texture is simply an unbalanced espresso. Bracing flavor notes are not progressive, they are merely a sign of an underdeveloped or improperly developed roast.
Every coffee (probably) can be used in espresso, but not every coffee can be used as espresso. Sometimes the flavors developed in a particular coffee are too intense as an espresso. But those same notes will often be a wonderful supporting note or highlight if the proper balance is achieved in a simple two or three bean blend.
Ok. That's all fine and dandy, but how does one properly execute a single origin espresso?
There are a handful of coffees that are amazing out of the gate single origin, single roast espresso. Many of these can be improved by profile layering, but it's really not necessary. That being said, the issues are rarely with the coffee, rather they are a result of poor execution of said coffee as a single origin espresso.
When a coffee has great flavors at City, City+, Full City, and Full City+, why ignore that potential complexity by utilizing a single roast? Multiple layers of flavor and an unmistakeable textural mouthfeel are what makes an espresso come alive.
It's not always about choosing light and medium or light and dark. Sometimes, it is about small differences within a certain darkness (City+ for example) of roast, but differing profiles. One roast might be more nut forward, one more fruit forward, and one more balanced. Not only should you think like a skilled chef or a world-class mixologist and weave layers within layers, you should take the same time to develop your craft as they did to develop theirs.
You can choose simplicity or complexity, but even within simplicity, there are supporting areas of sweet, savory or umami that give dimension to the espresso. To truly understand the flavor potential you need to explore the range of possibilities at your fingertips. There are as many ways to construct your espresso with a single bean as there are with two or three. Simplicity is not about taking shortcuts, simplicity is a focused exploration of what's in front of you.