Heat the olive oil in a cast iron skillet over medium-high heat. Add the onions, cooking until just starting to caramelize, about 10 minutes. Stir in the jalapenos, cooking until softened, about 5minutes.
Stir in the garlic. Sprinkle with cornstarch, whisk to combine.
Whisk in the beer and cream, reduce heat to a very low simmer.
Add the gouda and fonitna cheese, a hand full at a time, stirring until the cheese is well combined before adding more.
Stir in the salt, pepper, and hot pepper sauce. Remove from heat.
Preheat the broiler.
Sprinkle with the white cheddar, place the skillet under the broiler until the cheese is lightly browned.
Remove from oven, sprinkle with green onions, serve immediately (take care when serving, the pan will be very hot).