Preheat the oven to 400 degrees F (200 degrees C) and place oven rack in the middle of the oven.
In a small bowl, whisk together the Dijon Mustard (1/2 cup) and Buttermilk (1/2 cup). Place the Bone-in, Skin-on Chicken Thighs and Drumsticks (8) in a large bowl and pour the mustard-buttermilk mixture over top. Toss to coat.
Place the Garlic (4 clove), Fresh Thyme Leaves (1 handful), Lemon (1), Kosher Salt (1 dash) and Ground Black Pepper (1 dash) (or a few large cracks on the grinder) in a food processor fitted with the steel blade.
Process until the garlic is finely minced.
Add the Breadcrumbs (2 cup) and Olive Oil (1/4 cup), and pulse a few times to moisten the breadcrumbs. Pour the mixture into a wide, shallow bowl or onto a large plate — something with sides is best.
Line a sheet pan with parchment paper. Dip each piece of chicken skin-side down only into the crumb mixture, pressing gently to make the crumbs adhere. Place the chicken on the sheet pan crumb-side up.
Bake the chicken for 40 minutes.
Check on the chicken. If necessary cook another five minutes or until the crumbs are browned. Let rest 5 to 10 minutes before serving. Serve hot, warm, or at room temperature.