Preheat oven to 425°F.
Smash the garlic cloves, sprinkle with the 1 teaspoons salt, and with the flat side of a large knife, mash and smear the mixture to a coarse paste. Set half the garlic paste aside.
Melt the butter in a small saucepan. Set a v rack or regular rack in a roasting pan and brush with some of the melted butter. Stir the remaining garlic paste, the paprika, porcini powder, caraway seeds, and a generous amount of black pepper into the remaining melted butter and cook over medium heat, stirring until fragrant, about 30 seconds. Cool. Smear chicken cavity with reserved garlic paste, then stuff with the shallot and lemon zest. Brush spiced butter over chicken and season with salt.
Tuck the wings under the back, cross the legs, and tie them with kitchen twine. Place chicken breast side down on the rack and roast until the back is golden brown, 35-40 minutes.
Remove the pan from the oven and turn the chicken breast side up. Cut the string where it holds the legs together and gently spread the legs a bit. Baste the chicken with the pan drippings and roast again until the breast is golden brown and a meat thermometer inserted in the thigh registers 170°F, 20-25 more minutes.
Move chicken to a carving board and let rest for 10 minutes before carving.
To make sauce:.
Whisk the horseradish into the sour cream. Carve the chicken and serve with the sauce and Parslied Egg Noodles for a great Hungarian dinner!