Preheat the oven to 400 degrees F.
Make the compound butter by mixing 1 stick of the softened butter with the minced garlic and 1/4 cup of the chopped parsley. Set aside.
To make the butter sauce, squeeze the juice of 2 of the lemons into a shallow saucepan. Reduce by half over medium heat, then whisk in the remaining stick of butter until emulsified.
Spread a thin layer of the compound butter on each side of the bread slices. Put the bread on a large baking sheet in a single layer and toast until golden brown.
Meanwhile, heat a saute pan to medium heat and add the grapeseed oil. Add the sliced garlic and sweat. Add the chile flakes and cook for 20 seconds. Deglaze with the wine and reduce by about 10 percent. Add the remaining compound butter followed by the snow crab legs. Saute until the crab legs are warm, 1 minute, and then finish with the butter sauce, tossing together for a few minutes until combined.
Cut the remaining 2 lemons into wedges. Serve the crab legs with the toasted bread and lemon wedges on the side. Garnish with the rest of the chopped parsley.