Zest the orange directly into the half and half in a saucepan and heat over medium-low, stirring occasionally, until bubbles begin to break the surface, about 5 minutes. Remove from heat.
In a mixing bowl, whisk together egg yolks and honey until combined. Whisk in ½ cup of the heated mixture to warm the egg yolks, then whisk the egg mixture into the remaining orange sauce in the pan. Return to medium-low heat and continue to stir until sauce thickens and coats the back of a spoon, about 5 minutes.
Pour the sauce into a bowl set inside a larger bowl with ice to help chill the sauce quickly. Stir occasionally until cooled, about 10 minutes. Refrigerate until ready to serve. Just before serving, stir in Grand Marnier. Note: The orange cream can be made up to a week in advance.
For the berry filling:
Prepare 8x8 baking dish with 1 tablespoon butter. Arrange the berries in an even layer in the dish and sprinkle evenly with cornstarch, palm sugar, cardamom, and vanilla extract. (It doesn't matter if the berries are layered or mixed with the dry ingredients in a bowl--layering just saves washing an extra dish). Dot with remaining butter.
For the Crumb Topping:
Mix the almond flour, oats, palm sugar, and cinnamon in a bowl until well combined. Press the softened butter into the dry ingredients, mixing with your finger tips until combined and crumbly.
Sprinkle topping over the layered ingredients and bake for 30 minutes, until bubbly and browned. Serve with Orange Cream.
Cointreau or Tuaca can be substituted for Grand Marnier.
Leftover Orange Cream can be refrigerated for up to 1 week or frozen.
Serve as a substitute for syrup on waffles or pancakes.
Serve crumble over vanilla ice cream and drizzle orange cream on top.