Prepare the crostini by preheating the oven to 400°F (200°C).
Slice the French baguette into 1/2-inch thick pieces and arrange them on a baking sheet.
Brush each slice lightly with olive oil, then sprinkle with salt and pepper.
Bake the crostini in the preheated oven for about 8-10 minutes, or until golden.
While the crostini are baking, heat the remaining olive oil in a skillet over medium heat.
Add minced garlic and red pepper flakes to the skillet, stirring frequently for about 1 minute.
Add the shrimp to the skillet, seasoning with salt, pepper, and lemon juice.
Cook the shrimp for about 3-4 minutes, or until they turn pink and opaque.
Remove the crostini from the oven and spread a layer of mashed avocado on each piece.
Top each avocado spread with a generous portion of garlic shrimp and garnish with parsley.