Heat oven to 350 degrees.with a rack in center. Spread all the walnuts on a baking pan. Bake until fragrant, about 7 minutes. Transfer nuts to a bowl; set aside to cool.

Reduce oven heat to 325 degrees. Brush tartlet pans with melted butter. In a large bowl, whisk together the 12 tablespoons melted butter, sugar, eggs, almond extract, and flour. Batter will be thick. Stir in cranberries and 3/4 cup toasted nuts.

Fill each mold with 1/2 cup batter. Sprinkle each top with 1 teaspoon walnuts and amber sugar, if desired. Bake until golden and slightly crusty on top, 30 to 40 minutes. A cake tester inserted in the center should come out clean. Transfer to a cooling rack. Once cool, remove tarts from pans. These are best served within a day.