Heat oven to 350°F. Line an 8-inch square baking pan with parchment so that opposite edges hang over sides of pan and grease lightly. Whisk together flour, baking powder, salt and ginger; set aside.
In the bowl of an electric mixer beat the butter and sugar until fluffy, about 2 min. Add the eggs, one at a time, beating after each addition. Add the oil, lemon zest and vanilla and continue to mix until creamy, scraping sides of bowl as needed. Add the dry ingredients and mix until just blended.
Pour batter into prepared pan and arrange the sliced pineapple on the surface, overlapping slightly and pressing gently into the batter. Bake until done in the center, 45 to 50 min. Cool completely; transport in baking pan.
This cake is actually a very portable cake. Great for potlucks, spring parties and summer picnics. Keep it in the pan to travel and you have the perfect dessert...or snack.