Cranberry Bacon Jam:In a medium pot, cook the bacon until nicely browned. Remove from pot, saving about 2 tbsp bacon fat. (Strain the rest off of the bacon)
In remaining bacon fat, cook the onions over medium heat until translucent. Add garlic and cook about a minute until fragrant.
Add bacon back to the pot. Add remaining bacon jam ingredients (through to dried cranberries).
Cook over medium heat, stirring often (watch carefully so the sugar doesn't burn), for about 30 minutes until thickened and syrupy (there shouldn't be a lot of liquid remaining). Set aside. (This can easily be made ahead and stored in the fridge, but you may need to warm it before spreading!)
Crostini:Spray a baking sheet with non stick spray and preheat the oven to 400 degrees F.
Lightly butter one side of each bread slice, and place on baking sheet with the butter facing up. Place pan in the oven for 3-4 minutes, until the bottom is lightly toasted. Flip bread slices and top with cheese slices. Spoon about 1 tablespoon of bacon jam on top of cheese and place in the oven for 4-5 minutes, until the bacon jam is warmed through and the cheese is melted.
Top with chopped walnuts and parsley if desired.
I used a half baguette (160g) and got about 12 slices. A full baguette will likely get you about double, and that's what I've accounted for in the recipe. Feel free to make as much or as little as you want -- the bacon jam keeps well in the refrigerator and is great on sandwiches, pizza, or right off the spoon! The bacon jam can be made up to a week ahead, which reduces your prep at the time of your even.