The following recipe has always been a source of interest to me as my mother often spoke about it with some nostalgia, however when she made a cake and referred to it as Teisan lap I remember her cake being more like a flat oatmeal cake.
The following then is a more traditional recipe, which was apparently popular in South Wales as it was home cooked fare sometimes included in a miner's lunchbox. It could have been cooked in a Dutch oven or in front of the open fire either in a tray or on an enamel plate.

Teisen lap (meaning crisp and moist cake) 8-9inch cake

9 oz plain flour
1.5 tsp baking powder
1/2 tsp grated nutmeg
4.5 oz butter cut into cubes
4.5 oz caster sugar
4.5 oz currants or sultanas
2 eggs lightly beaten
1/4 pt milk or buttermilk
Mix all the dry ingredients and fruit and rub in the butter to the breadcrumb stage.
Add the beaten eggs and the milk to give dough a soft moist consistency.
Place the mixture in a round baking tin.
Bake cake at 190deg C for 30-40 minutes.
Turn out onto a wire rack after 5 mins.
Can be served warm or cold.
Alternative ingredient could be substituting the currants or sultanas for chopped dried apricots.