Preheat the oven to 190C/170C fan. Line a 12-hole (1/3cup/80ml) muffin pan with paper cases.
Blend Natvia in a high-speed blender until the consistency of icing sugar. Reserve 2 tsp.
Sift powdered Natvia, flour, spices, and soda into a bowl.
Whisk egg whites in a medium bowl with a fork until frothy. Add butter, almond meal, sifted dry ingredients and zest. Stir until just combined. Add dried currants, stirring until combined. Spoon mixture into paper cases.
Bake 25 minutes until skewer inserted into centres comes out clean. Stand in pan 5 minutes then transfer to a wire rack to cool.
SPICE SYRUP: Place tea bag in a small heatproof jug. Pour over boling water. Stand 5 minutes to infuse. Remove tea bag. Place vanilla bean and seeds, Natvia and mixed spice in a medium saucepan. Stir to combine. Add tea. Cook, stirring, over low heat 2 mins until Natvia dissolves. Bring to the boil. Reduce heat to low. Simmer, uncovered, without stirring, for 5 minutes until syrup thickens slightly. Remove from heat and discard vanilla bean. (Don't worry if the syrup recrystallises as it cools. Just reheat over low heat until it dissolves)
Top friands with creme fraiche and red currants. Drizzle with hot syrup and dust with reserves sifted powdered Natvia.