Make roses: Chop white chocolate. Microwave in 15-second bursts, stirring between, until mostly melted. Stir until smooth. Dip toothpick into oil-based coloring and touch to chocolate. Stir. Add more drop by drop until desired shade. Fill rose molds completely. Tap to release bubbles. Let set 30 minutes at room temperature or 15 minutes in fridge. Gently flex mold to release roses. Set aside.
Brown butter: Place butter in light-colored saucepan over medium heat. Swirl as it melts, foams, and turns amber with brown specks. Once nutty and toasty, immediately remove from heat and pour into large bowl. Cool 10-15 minutes.
Mix wet: To cooled brown butter, add brown sugar and granulated sugar. Beat with electric mixer 2-3 minutes until smooth. Add egg and vanilla, beat until creamy and glossy.
Mix dry: In separate bowl, whisk together flour, baking soda, and fine sea salt.
Combine: With mixer on low, gradually add dry ingredients to wet. Mix just until combined and no flour streaks remain. Do not overmix.
Add chips: Fold in semi-sweet chocolate chips with rubber spatula until evenly distributed.
Scoop and freeze: Scoop dough into 2½-tablespoon portions (16 cookies) or 3-tablespoon portions (12-14 cookies). Place on parchment-lined plate. Cover tightly with plastic wrap. Freeze 24 hours.
Preheat and prep: When ready to bake, preheat oven to 190°C (375°F). Line baking sheet with parchment. Have roses ready next to oven.
Bake: Place frozen dough balls on prepared sheet, 3 inches apart. Bake 11-13 minutes until edges golden and set, centers still soft.
Wait 10 minutes: Let cookies cool on baking sheet for exactly 10 minutes.
Add roses: Gently press one rose onto each cookie. Press just enough that base makes contact, petals should remain visible.
Refrigerate: Slide entire baking sheet into fridge for 15 minutes.
Transfer and serve: Remove from fridge. Transfer to wire rack or serve. Store in airtight container.
