Preheat the oven to 400 degrees F.
Heat the olive oil in a skillet over medium-low heat. Add the garlic and cook for 30 seconds. Add in the spinach and cook down until it’s completely wilted, about 5 to 6 minutes.
In a bowl, mix together the cream cheese, sour cream, artichoke hearts, half of the cheddar cheese and all of the parmesan. Add a big pinch of salt and pepper. Mix in the spinach from the pan until thoroughly combined.
Line a baking sheet with parchment paper. Slice a grid pattern into the loaf of bread, leaving about an inch uncut at the bottom of the loaf. I find it easiest to slice longways and then go back and slice the rest of the grid. Do not worry if any pieces fall out - just stuff them back in!
Gently pry apart the bread squares. Drizzle/brush 3 tablespoons of the melted butter into the crevices of the bread and on top. Gently pull apart the bread again and stuff the spinach artichoke mixture into the crevices. I use a bread knife to push it down inside each slice. This does take awhile because you want to do it gently and carefully! Stuff as much into the bread - every slice - that you can!
When done, go back and stuff some of the remaining cheddar inside or even just pile it on top. Drizzle the remaining butter all over the bread.
Bake for 15 to 20 minutes, until it’s golden and cheesy and toasty. Remove and sprinkle with fresh parsley. Serve immediately!