Almond Crusted Croque Monsieur with English Tea Bechamel Sauce

Name: Almond-Crusted Croque Monsieur with English Tea Bechamel Sauce
Ingredients: 1 quart (32-ounces) whole milk, 1/4 cup reserved; 1 English breakfast tea bag; 2 tablespoons chopped fresh tarragon; 2 tablespoons oil; 2 tablespoons butter, plus 3 tablespoons for sauce; 3 eggs; 3 tablespoons kosher salt; 1 teaspoon freshly ground black pepper; 1 cup blanched, sliced almonds; 1 baguette, sliced into 1/2-inch pieces; 1 baked ham, sliced really thin; 2 cups shredded sharp Cheddar or Swiss cheese; 1/2 cup chopped yellow onion; 2 tablespoons all-purpose flour; 2 tablespoons grated Parmesan cheese; 1/4 cup chopped fresh parsley