Preheat the oven to 175 degrees Celsius. Butter 5 ramekins and set aside.
Line a 9-inch baking tray with parchment paper and spread the 70 grams walnut pieces in a single layer on the tray. Toast the nuts for 8 - 10 minutes until they are lightly browned and the whole kitchen is filled with a nutty aroma. Don't let the nuts burn! Remove the baking tray from the oven and set it on a wire rack to cool completely.
When the walnuts have cooled, place them into a food processor with 1 tablespoon of caster sugar and process it into a fine paste. Add in the lemon peel / zest and process it until fully incorporated.
Place the flour, baking powder and salt in a small bowl. Stir to disperse the baking powder and salt thoroughly. Add in the walnut paste and stir the mixture together, pressing the walnut paste as you mix to remove as much lumps as possible. Alternatively, add the flour mixture into the food processor with the walnut paste and process until smooth.
Place the remaining sugar, butter, honey and vanilla in a medium mixing bowl. Cream the mixture until light and fluffy, about 4 to 5 minutes, scraping down the sides occasionally. Scrape down the sides and add in one egg. Cream for 1 minute, scrape down the sides and add in the second egg. Cream for 1 minute and scrape down the sides. Turn the mixer on low and add in the flour-walnut mixture in two batches, beating until fully incorporated. The batter will turn a light brown colour.
Divide the batter among the 5 ramekins. Sprinkle the chopped walnuts on top if desired. Bake for 20 - 25 minutes until the top is golden brown and a skewer inserted into the centre of the cake comes out clean.
Serve the cakes warm or at room temperature with a dollop of whipped cream or a scoop of good-quality vanilla ice cream. To turn out the cakes, run a butter knife along the edges of the cake and turn it over onto a serving plate. Give the bottom a few light hits and the cake should come out easily.