Adjust rack to the middle of the oven, preheat to 350 F / 175 C. Prepare a 8 inch x 3 inch high round cake pan, line the bottom with a piece of round parchment paper. Do not grease the sides of the pan as the batter needs to climb up as it bakes.
Sift together flour and baking powder. In a medium bowl, whisk egg yolks lightly, add olive oil and water, and clementine zest, whisk to combine. Mix in sifted flour mixture until incorporated, do not over-mix. Set aside.
In the mixer bowl, beat together egg whites and sugar. Start on low speed and increase to high speed slowly. Beat until meringue reaches a stiff peak.
Take one-third of the meringue and fold into the flour mixture until incorporated. Gently fold in the rest, careful not to deflate the batter too much. Pour into the prepared pan.
Bake in preheat oven for 40-45 minutes until a skewer inserted in the middle and comes out clean. Cool completely in pan before unmoulding and slicing.
Meyer Lemon Curd + Glaze
In a medium saucepan, whisk together sugar and egg yolks until combined, whisk in the lemon juice and zest.
Heat the mixture on medium heat, keep whisking to prevent the bottom from burning. Cook the curd for about 10-15 minutes, until the curd coats the back for a spoon. Take off heat and whisk in butter until it is emulsified.
Strain lemon curd through a fine mesh sieve into a clean container. Cover and chill until ready to use.
Glaze: Mix icing sugar and lemon juice in a bowl, set aside until ready to use.
Assembly: Slice cake horizontally into three equal slices. Place the first slice on a plate or platter, spoon about 1/3 of the lemon curd and spread it evenly. Layer with the other two slices of cake and lemon curd. Spoon the glaze all over the top, grate clementine and lemon zests on top, and decorate with cut fruit. Sprinkle with dried rose petals if desired. Let the glaze set for 15 minutes for serving.