Preheat an oven to 450 degrees.
Heat a large sauce pot on medium heat and add the butter and olive oil. When they are melted add the garlic, jalapenos, onion, red bell pepper and fennel. Add a little cracked black pepper and the bay leaf. Stir and allow to cook until very fragrant, about 5 minutes. Now add the clams, shrimp and wine. Cover the pot. Turn the heat to high. Let the clams steam open and remove them to a bowl as they do. Remove the shrimp too. Turn off the heat and allow the broth to cool a little.
Remove the clams and shrimp from their respective shells. Cut the shrimp into bite sized pieces and reserve with the clams for later.
Strain the vegetable and clam liquor and reserve combined with the chicken stock. Warm them both together in a separate pot. Clean out the sauce pot and return it to the stove. Turn the heat on to medium and add the reserved 3 tablespoons virgin olive oil. When it is warm add the rice and stir well to coat all of the grains.
Begin adding the reserved the liquor/stock mixture by adding 1 cup of it first, stirring constantly allowing it to become almost entirely assimilated by the rice. Now add in the next 1/4 cup of stock/liquor and the saffron and stir again. Repeat stirring and add all of the broth and stock until all of it is absorbed. Season to taste. Fold in the cooked shrimp and clams.
Spoon this mixture into the poblanos and place them on a nonstick baking sheet pan and warm through. Serve immediately
Additional vegetable garnishes could be folded into the paella rice if you like. Cooked shelled sweet peas, roasted bell pepper(s) strips, cooked mushrooms and or corn kernels etc.