Step 1Trim the tops and stems of the artichokes. Stand the artichokes upright in a steamer, and steam until a leaf easily pulls out from one of them, about 45 minutes. Remove the artichokes; when cool enough to handle, remove the leaves and discard. Scoop out the chokes with a spoon. Peel and remove any tough skin from the stems and bases of the artichokes, placing the cleaned bottoms in a bowl of water with the juice of half of a lemon as you work.
Step 2Cut the bottoms into quarters. Pulse in a food processor until pureed but slightly chunky. Add the olive oil, pulsing to mix.
Step 3Spoon the mixture into a small bowl, and stir in the olives, garlic, 1 teaspoon lemon juice, minced thyme and salt and pepper to taste. Spoon into a serving bowl and garnish with thyme sprigs. Serve with toasted French bread slices.