In a medium bowl, whisk together sugar, flour, and salt. Add eggs and egg yolks, whisking until mixture is smooth.
In a medium saucepan, heat coconut milk over medium heat until bubbles begin to form around edges of pan. Whisking egg mixture constantly, gradually add half of coconut milk to egg mixture, whisking until smooth. Gradually whisk in remaining coconut milk until smooth. Return all coconut milk mixture to saucepan, and cook over medium heat, stirring constantly, until mixture is slightly thickened, about 6 minutes. Whisk in butter and vanilla extract.
Pour mixture into a heatproof bowl. Cover with plastic wrap, pressing wrap directly onto surface of custard to prevent a skin from forming. Refrigerate until mixture is very cold, at least 4 hours or up to 3 days.
Spoon coconut mixture into Macadamia Nut Crusts, smoothing tops. Garnish with mango slices, strawberry halves, raspberries, blueberries, blackberries, mint, and edible flowers, if desired. Serve immediately.
Recipe by Victoria at https://victoriamag.com/miniature-coconut-cream-macadamia-nut-tarts-recipe/