Preheat oven to 350°F. Line two baking sheets with parchment paper or silicone baking mat. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter until smooth. With the mixer running on medium speed, slowly add in sugar. Mix until incorporated.
Add egg and vanilla. Continue to mix on medium speed until well combined. Scrape down sides of bowl as needed to ensure thorough mixing.
In a separate bowl, whisk together flour, cake flour, and baking powder. Add flour mixture to mixer in two additions. Mix on low speed until there are no longer any dry streaks of flour.
Transfer cookie batter to large piping bag (18-inch) with fitted a ½-inch open star tip (also labeled as #826 tip). Pipe 2-inch rosettes (or rounds/circles, stripes, or S-shapes) on prepared baking sheet. Space cookies at least 2-inches apart.
Bake for 15-18 minutes, rotating sheet midway through baking. Bake until edges are lightly golden brown. Let cookies cool in baking sheet for about 5 minutes before transferring to wire rack to cool to room temperature.
Store cooled cookies in an airtight container. Cookies will keep at room temperature for up 5 days.