Prepare the dipping foods by bringing the chicken stock to a boil in a sauce pot. Add the broccoli, cauliflower, asparagus and green beans and cook for 2 minutes. Using a slotted spoon, strain out the vegetables, reserving the broth. You will use 1/4 cup of this reserved broth in the fondue, but save the rest for another use.
In a large bowl, toss together the shredded cheddar, shredded gouda and the flour until flour is coating cheese evenly. Set aside.
Take the thawed chopped spinach in your hand and squeeze as much water as you can out of the spinach. Set aside.
Heat a fondue pot or medium pot over medium heat with the butter and bacon. Cook the bacon for 2 minutes (make sure the bacon does not burn or cook too quickly). Add the garlic and mushrooms and saute until the mushrooms are softened, about 2 minutes. Pour in wine and 1/4 cup of the previously reserved chicken broth from step 1. Bring to a simmer and in batches, add a handful of the cheese, stirring and letting the cheese melt before adding more. Stir in the chopped spinach. If the fondue becomes too thick, add a couple tablespoons of additional broth.
Serve fondue with the vegetables, apples and bread.