Preheat oven to 300°. Lightly coat 6 (4-ounce) tall-sided ramekins** with cooking spray. Wipe out excess spray. Place ramekins in a deep baking dish with tall sides. Fill a large heatproof bowl with ice.
In a medium sauté pan, stir together ½ cup sugar, 2 tablespoons water, and lemon juice until combined. Cook over medium-high heat until mixture is a medium amber color, 3 to 4 minutes. Working quickly, remove pan from heat and place on top of ice in prepared heatproof bowl to stop caramel syrup from cooking. (Cool for only a very brief time so that syrup does not harden.)
Divide syrup among prepared ramekins, making sure bottoms of ramekins are completely covered.
In a medium bowl, whisk together egg yolks, eggs, and salt until combined. Add milk, cream, vanilla extract, and remaining ½ cup sugar, whisking until sugar dissolves.
Using a fine-mesh sieve, strain egg mixture into a large liquid-measuring cup with a pouring spout. Divide egg mixture among prepared ramekins, covering caramel syrup.
Carefully fill baking dish with boiling water halfway up sides of ramekins. Cover baking dish with foil.
Bake until custards are somewhat firm but centers are jiggly and a tip of a knife inserted in centers comes out mostly clean, approximately 80 minutes**. Using tongs, carefully transfer ramekins to a wire rack. Let cool completely. Place ramekins in a covered container and refrigerate overnight.
When ready to serve, run the tip of a small knife around edges of each custard. Dip ramekins for a few seconds into a bowl of very hot water, so water comes halfway up sides of ramekins, to release custards. Place a dessert plate over each ramekin then invert so that custard drops onto plate with syrup.
Garnish each serving with edible flowers, if desired. Serve immediately.
Notes
* We used edible jasmine flowers from Gourmet Sweet Botanicals, 800-931-7530, gourmetsweetbotanicals.com.
**We used Le Creuset 2-inch-tall (4-ounce) ramekins. If shallower ramekins are used, baking time will be less.
Recipe by TeaTime Magazine at https://teatimemagazine.com/creme-caramel/