Step 1Cut the cod into pieces. Place in a large, deep skillet with enough water to cover and add the bay leaf. Poach at a slow simmer. Cook until the cod flakes easily, about 25 to 30 minutes. Remove the cod from the pan with a slotted spoon, leaving the water to simmer gently.
Step 2Heat three-fourths cup of oil and the milk in separate saucepans.
Step 3In a food processor with the motor running, drop the garlic through the feed tube to mince. Stop the machine, add the cod and pulse to make a fine puree. Scrape down the sides and then, again with the motor running, add the oil and the milk in thin streams, processing until thoroughly incorporated. Stop and scrape down the sides as necessary. Add the lemon juice and pulse once or twice to combine, then taste and correct the seasoning, adding more lemon juice or salt as needed.
Step 4Remove the green parts of the Swiss chard, leaving just the white stems. Reserve the leaves for another use. Trim the dried bottoms and chop coarsely. Cook the chard in the same water in which you cooked the cod at a low simmer until just tender, about 10 minutes. Drain the chard and chop into thin pieces.
Step 5Heat the oven to 400 degrees. Butter 6 (6-ounce) ramekins. Place about 3 tablespoons of the chopped chard in the bottom of each, then about 3 tablespoons of the brandade, patting gently with the back of the spoon after each addition to smooth the top. Repeat with a layer of chard and another layer of brandade until all is used.
Step 6Scatter about 1 tablespoon of bread crumbs across the top of each ramekin and drizzle with a fine thread of olive oil. Bake until the tops are well browned and the filling is bubbling hot, about 20 to 25 minutes. Serve immediately.