In a large mixing bowl, or bowl of a stand mixer, beat 1 1/2 cups granulated sugar, the ½ cup unsalted butter, and the ½ cup shortening until fluffy.
Add in the 2 large eggs one at a time, followed by 1 teaspoon almond baking emulsion
Sift together the 2 ¾ cup all-purpose flour,2 teaspoons cream of tartar, 1 teaspoon baking soda and ¼ teaspoon salt. Add to wet ingredients, only mix until just combined.
Chill dough at least 1 hour. Once dough as been chilled, roll into uniform sized balls of dough and roll in remaining 1/2 cup granulated sugar,
Place on baking sheets lined with parchment paper or a silicone baking mat and bake at 375℉ for 8-10 minutes. Cool cookies on pan 2-3 minutes then move to wire rack to cool completely.
Combine the 2 cups powdered sugar and 2-3 teaspoons water (enough to make a drizzling consistency). Add in the remaining 1/2 teaspoon almond extract or baking emulsion
Drizzle glaze over cooled cookies, sprinkle with slivered almonds. Allow glaze to set completely before serving.