Generously oil a high-sided 8 inch tart pan with removable bottom. Set aside.

In bowl, soak pitted dates in boiling water for 10 or 15 minutes until softened. Drain well. Reserve liquid for smoothies if you wish. Lightly blot dates dry and cut into halves. Place in a food processor fitted with a metal blade along with toasted walnuts, cocoa and sea salt. Pulse until fully blended and ingredients begin to clump together. Transfer to oiled tart pan and press out with fingertips into an even thickness across the base and up the sides of the pan.

Melt chocolate in a small microwave-safe dish in 30 second increments, stirring until pourable. Drizzle onto bottom of prepared crust and using an offset spatula or the back side of a spoon, spread chocolate evenly over bottom of tart shell. Transfer pan to freezer. While crust hardens, make filling.

In medium saucepan combine thawed raspberries, maple syrup, orange zest and vanilla. Cook over medium-low heat, stirring until it begins to simmer, and raspberries break down. Remove from heat and keep stirring to slightly cool. Transfer to a blender. Whirl until almost smooth. Return to saucepan and stir in chia seeds. Set aside and cool to room temperature.

When raspberry filling is cooled, spread evenly in partially frozen chocolate tart shell. Return to the freezer for 45 minutes to fully set. Then remove to refrigerator. Cover until just before serving.

To serve, pop base from sides of tart pan. Place 1 oz in microwavable small bowl and heat for 30 seconds. Stir and repeat in 10 second increments until melted. If adding fresh fruit, arrange over top of raspberry filling. Drizzle with melted chocolate. Garnish with flaked salt if you wish.