1. Take the butter out of the refrigerator an hour in advance.
2. Remove the stems from the parsley, wash the leaves and dry them in a clean tea towel. Chop them in a blender, adding 100 g of butter in small pieces after the first few turns. Season the parsley butter with salt and pepper. Set aside in a cool place.
3. In a medium saucepan, bring some water to a boil and salt it (1 tbsp. coarse salt per litre). Break the garlic heads apart and separate the cloves. Do not peel them. Put them into the boiling water and leave for 2 minutes. Drain and peel.
4. Discard the water. Put the garlic cloves back into the saucepan, cover with cold salted water and bring to the boil. Boil for 7 to 8 minutes. Repeat this procedure 5 or 6 times.
5. Drain the cooked garlic cloves and split them in half. Remove the green germ in the centre of each clove. Put the cloves into a blender and blend into a smooth purée. Return the purée to the saucepan. Add the milk and season with salt and pepper.
6. Cover the saucepan and keep warm.
7. Season the frog's legs with salt and pepper. In a large skillet, heat the oil and the remaining butter. Add the frog's legs and sauté over high heat for 3 to 4 minutes, until they are nicely browned.
8. Meanwhile, bring 2 tbsp. water to a boil in a small saucepan. Add the parsley butter in several stages, whisking briskly.
9. Correct the seasoning and add a dash of lemon juice.

Presentation

1. Drain the frog's legs on paper towel.
2. Pour the parsley sauce into a deep heated dish.
3. Place the garlic purée in the centre and arrange the frog's legs around it.