Itty-Bitty Sandwich Cookies

Name: Itty-Bitty Sandwich Cookies
Ingredients: Cookies; ½ cup (113 g) unsalted butter, at room temperature; ½ cup (99 g) granulated sugar; 1 large egg yolk; 1 teaspoon pure vanilla extract; 1½ cups (180 g) all-purpose flour; ⅓ cup (28 g) cocoa powder; ¼ teaspoon baking soda; ¼ teaspoon fine sea salt; Filling; 4 tablespoons (57 g) unsalted butter, at room temperature; 2 ounces (57 g) cream cheese, at room temperature; 2 cups (227 g) confectioners’ sugar; 1½ tablespoons heavy cream